The ultimate Codex tutorial for beginners (GPT 5.5 edition)

Codex is one of the most powerful AI tools available right now. Powered by the GPT 5.5 model, it doesn’t just answer questions—it can plan, execute, and even operate your computer and browser like a real teammate. If you’re new to Codex, this guide will walk you from installation to building a complete mini project: a newsletter landing page, automated email content, a marketing plan, and a promo video.

What Codex is and why it’s different

Codex is an AI desktop app from OpenAI that combines advanced language models (like GPT 5.5) with direct access to your computer and online tools. Instead of just chatting, it can:

• Use your browser to open sites, test pages, and take screenshots
• Read and organize files on your computer (with your permission)
• Connect to tools like Google Drive, Gmail, GitHub, and Slack
• Plan multi-step tasks and then execute them end-to-end

Compared with other models like Claude or Gemini, Codex is optimized for doing real work: building interfaces, running automations, and coordinating multiple tools in one workflow.

How to download and install Codex

To get started, you’ll need to install the Codex desktop app.

1. Go to chat.openai.com/codex in your browser.
2. Click Download for macOS (Windows support may vary depending on when you’re reading this).
3. Once the download finishes, open the file and drag the Codex icon into your Applications folder.
4. Launch Codex from Applications.

On first launch, you’ll go through a short onboarding flow:

• Choose what type of work you do (engineering, product, marketing, etc.) so Codex can tailor suggestions.
• Sign in with your existing ChatGPT account so it can bring in your previous projects and tools.

Understanding permissions and access

When Codex starts, it will ask for access to certain folders and documents on your computer. Granting access allows it to:

• Open and edit files
• Organize documents related to a project
• Run more complex workflows across your system

You can also control Codex’s overall access level for each chat or project:

• Default: Runs in a secure sandbox with limited access to your machine.
• Auto review: Codex can attempt more powerful actions but will ask you to review sensitive steps before executing them.
• Full access: Gives Codex broad control over your computer so it can work more autonomously.

For most people, starting with Auto review is a good balance of power and safety.

Getting familiar with the Codex interface

Once you’re in, you’ll land on the New chat page. This is your main workspace.

Key areas to know:

Left sidebar
• New chat: Start a fresh conversation or task.
• Search: Find any of your previous chats.
• Projects: Think of these as folders for related work—an app, a website, a client, or a business idea. Keeping everything in a project gives Codex more context.
• Chats: One-off or ongoing conversations that aren’t tied to a specific project.

Plugins / connectors section
• This is where you connect external tools (browser, computer control, Google Drive, GitHub, Slack, etc.).
• You’ll use this area to give Codex the ability to act across your apps.

Automations
• A dedicated page where you can schedule tasks—like having Codex read your email every morning and send you a summary at 9:00 a.m.

Model and quality settings
On the right side of the chat input, you can choose the model and quality:

• Model: GPT 5.5 (the latest Codex model in this tutorial).
• Quality: Low, Medium, High, or Extra high.

High is usually the sweet spot: strong reasoning and accuracy without being too expensive in tokens.

Attachment and tools button
Next to the chat box, the + button lets you:

• Add photos or files
• Enter plan mode (have Codex plan before acting)
• Choose which plugins or connectors to use for that task

Setting up connectors and skills

Connectors are how Codex talks to the rest of your digital world. They turn Codex from a smart chatbot into a true AI agent that can operate tools for you.

Popular connectors include:

• Computer use: Lets Codex control your desktop, open apps, and interact with windows.
• Browser use: Lets Codex browse the web, test websites, and take screenshots.
• Google Drive: Create and edit Docs, Sheets, and Slides.
• Gmail: Draft and send emails.
• GitHub: Work with repositories and code.
• Slack: Send messages and manage channels.
• Hyperframes by HeyGen: Generate motion graphics and promo videos.

To add a connector:

1. Click the + in the plugins/connectors section.
2. Choose the connector you want (for this tutorial: GitHub, Computer use, Browser use, and Hyperframes by HeyGen).
3. Follow the on-screen steps to authorize access.

Using Codex as your AI teammate

The best mental model for Codex is: a capable teammate who can use almost any software tool you give it access to. Instead of doing everything manually, you describe what you want, and Codex:

• Breaks the work into steps
• Plans the implementation
• Executes those steps across your tools
• Tests and verifies the results

To see this in action, let’s walk through a complete example project: launching a simple AI newsletter.

Example project: build an AI newsletter landing page

We’ll ask Codex to create a basic landing page for a fictional newsletter called “Armri’s AI newsletter.” The goal: a modern, clean, beginner-friendly page with a green color scheme.

Step 1: Plan the landing page

Start a new chat (or project) and enable plan mode. Then give Codex a clear prompt, such as:

“Create a simple landing page for an AI newsletter business called ‘Armri’s AI newsletter.’ Make it modern, clean, and beginner-friendly with a green color scheme. Include a headline, sub-headline, email sign-up box, feature section, and a clear call-to-action button. Use plan mode first to outline the implementation before building.”

Codex will respond with a structured plan describing what it intends to build: layout, sections, styling, and behavior.

Once you’re happy with the plan, confirm with something like: “Yes, implement this plan.”

Step 2: Let Codex build and test the page

Codex will then:

• Create the landing page in an empty workspace or project
• Use the browser connector to open and render the page
• Take screenshots to verify layout and design
• Run basic tests, such as clicking the sign-up button to ensure it works

Behind the scenes, Codex 5.5 can also tap into the GPT Image 2 model to generate visuals or illustrations if needed, giving your landing page a more polished look.

Automating your newsletter with Codex

Once the landing page is done, you can use Codex to automate the content itself.

Create a daily newsletter automation

1. Open the project or chat for your newsletter landing page.
2. Click the three dots for that project/chat and select Add automation.
3. Describe what you want the automation to do. For example:

“Every day, create an AI newsletter with simple, practical lessons for beginners. Pull recent information from articles, YouTube videos, and other reliable AI news sources. Summarize the most important updates and turn them into an easily digestible, actionable email.”

4. Set the schedule—e.g., Daily at 9:00 a.m.
5. Save the automation.

You can test it immediately by going to the Automations page, selecting your new automation, and clicking Run now. Codex will then generate a complete newsletter issue based on the latest AI developments.

To go even further, you can create a second automation that sends the generated email directly to your mailing list using your email tool or Gmail connector.

Improving your landing page with Codex

After seeing the first version of your landing page, you might want to refine the design and copy. Instead of manually tweaking everything, you can ask Codex to audit and improve it.

In the same project, give Codex a prompt like:

“Review the landing page you created for Armri’s AI newsletter. Evaluate the UI (layout, spacing, colors), the copy (headlines, sub-headlines, body text), and overall clarity. List specific improvements, then implement those improvements directly.”

Codex will:

• Analyze the page structure and visuals
• Suggest clearer headlines and more compelling copy
• Adjust spacing, typography, and layout
• Apply the changes and re-test the page

You’ll often see Codex’s cursor moving in the app or on your screen as it edits and refines the design.

Let Codex create your marketing plan in Google Drive

With the Google Drive connector enabled, Codex can also handle strategy work—not just implementation.

Ask it something like:

“Create a new Google Doc with a full marketing plan for Armri’s AI newsletter. Include an executive summary, target audience, positioning, acquisition channels, content strategy, launch plan, and metrics to track.”

Codex will:

• Create a new Google Doc in your Drive
• Draft a multi-page marketing plan (often 10+ pages)
• Cover positioning (e.g., beginner-friendly AI lessons for professionals, founders, students, and curious learners)
• Outline specific tactics across email, social, partnerships, and more

You’ll get a shareable link to the document, which you can open, edit, or hand off to your team. If you’re new to AI-powered productivity, this pairs well with broader beginner guides like this ChatGPT tutorial for beginners.

Generating a promo video with HeyGen Hyperframes

To complete the funnel, you can have Codex generate a short promo video for your newsletter using the Hyperframes by HeyGen connector.

In your project, prompt Codex with something like:

“Using HeyGen Hyperframes, create a ~30-second promo video for Armri’s AI newsletter. The motion graphics should tease the new Codex with GPT 5.5 and encourage viewers to sign up. Show a five-step sequence of different things Codex can do. Match the green color scheme of the landing page and ensure no graphics overlap awkwardly.”

Codex will:

• Plan the video structure (intro, key benefits, call to action)
• Generate motion graphics using Hyperframes
• Watch the video back, fix layout issues, and re-render if needed

The result is a ready-to-use 30-second promo video. You can:

• Add background music
• Record a voice-over or have an AI voice read the script
• Edit it in your favorite video editor
• Use it for social media, your website, or ads

If you’re interested in more AI-powered website and funnel building, you may also like our guide on creating a full site with Wix Harmony: AI website full tutorial for beginners 2026.

How to get the most out of Codex

The real power of Codex comes from experimentation. A few practical tips:

• Think in projects: Group related work (site, newsletter, product) into projects so Codex has full context.
• Use plan mode: Let Codex outline its approach before acting—this makes complex tasks more reliable.
• Start with clear prompts: Describe your goal, audience, style, and constraints (colors, tone, length).
• Iterate: Ask Codex to review, critique, and improve its own work (design, copy, structure).
• Leverage automations: Anything you find yourself doing repeatedly—summaries, reports, newsletters—can likely be automated.

With GPT 5.5, Codex can now handle longer, more complex workflows with higher accuracy than earlier generations. It’s capable of building interfaces, writing strategy docs, coordinating tools, and running on a schedule—all from natural language instructions.

Next steps

If you’ve followed this tutorial, you’ve seen how Codex can:

• Install and connect to your tools
• Build and improve a landing page
• Generate and automate a daily AI newsletter
• Create a detailed marketing plan in Google Docs
• Produce a polished promo video with motion graphics

From here, the best next step is to apply the same pattern to your own ideas—whether that’s a SaaS product, a personal brand, or a side project. Start small, let Codex plan before it acts, and keep iterating. The more you experiment, the more Codex starts to feel less like a chatbot and more like a real teammate helping you ship faster.