Install AI on your computer and give it permission to code

You have an idea. Now you need AI to work with files on your computer: create a page, change it and show you the result.

In the article that opens this series, I proposed nine steps. This is the first. We are going to install the tool, choose a folder and give it permission to start. The instructions were checked against official documentation on 30 October 2026.

You can do this with Codex, inside the ChatGPT desktop app, or with Claude Code, inside Claude. Choose one. That is enough for this first test.

Before downloading

You need an internet connection and an account with your chosen service. These are the entry-level individual plans:

• Codex: Free costs $0; Go costs $8 a month. Desktop access depends on the rollout available to your account. ChatGPT Plus costs $20 a month and expands access.
• Claude Code: requires a paid subscription. Claude Pro costs $20 a month with monthly billing, or $200 for a year paid upfront. Free lets you chat, but does not include Claude Code.

These are reference prices in US dollars. Check the currency and taxes when subscribing; Anthropic lists prices before tax. You do not need the higher plans to start. Codex plans and Claude plans.

ChatGPT offers a desktop app for macOS, Windows and Linux. On Mac it requires macOS 14 or later, with Apple Silicon or Intel. On Windows, download the new app. Linux has a distribution-specific guide.

Claude requires macOS 13 or later, Windows 10 or later or, in the Linux beta, Ubuntu 22.04 LTS or Debian 12 onwards, on x64 or ARM64. Download the installer for your processor.

Create an empty folder called mi-primera-web. Put it somewhere you can find it. That will be your workbench.

Option A: Codex in ChatGPT

1. Open the official ChatGPT download page. Choose the desktop app for your system and install it. Look for the new app, which brings ChatGPT and Codex together; the previous one appears as ChatGPT Classic.
2. Open ChatGPT and sign in. If you already pay for a subscription, use that same account.
3. Choose Codex and go to Projects to add a local project for this exercise.
4. Connect the mi-primera-web folder to the local project. In Projects, the project menu lets you open Edit project and use Add folder. Check that the selected folder is the one you just created. A ChatGPT project with attached files is not the same as a local folder.
5. Inside that project, start a conversation with New chat. Below the box where you type, open the permissions control and select Ask for approval. Check that it is selected for this conversation.

What have you just allowed? Codex can work inside that folder. It can create and modify files without asking about each edit. It requests approval for actions outside that scope, such as editing external files or using the internet.

The menu also offers Approve for me, which sends eligible requests for automatic review; Full access, which allows unrestricted access to files and the internet; and Custom (config.toml), for a custom configuration. Availability depends on the environment. For this test, I recommend Ask for approval. OpenAI permissions.

Option B: Claude Code in Claude

1. Go to the official Claude download page. Install the version for your system, open the app and sign in with your paid account.
2. Open Code, at the top of the sidebar. If you only see icons, hover over them to read their names. The app already includes Claude Code.
3. Below the prompt box, open the environment selector. Under Local, choose the entry for your computer. Beside it is the folder control: select Open folder… and open mi-primera-web. In earlier versions, the environment selector appears above the box.
4. Open the permissions selector and choose Manual.

The four modes you need to recognise are:

• Manual: asks permission before editing files or running commands; you can accept or reject each change.
• Plan: examines the project and proposes a plan without editing the source code. It can run commands to explore.
• Accept edits: automatically accepts edits and some file operations; it still asks about other commands.
• Auto: reduces prompts by automatically checking actions. It appears when available.

Start in Manual to see what it does and decide for yourself. If you want to study an idea first, use Plan and switch to Manual when you want to carry it out. Official desktop guide and permission modes.

Your first task

Start small. I started with Sites, creating a website. Then I jumped into an offline document pseudonymiser. A complex project. Perhaps bigger than I should have chosen.

The website taught me how to work with AI. The pseudonymiser taught me what a large project costs when you are still learning. That is why your first task needs to be something you can open and check in five minutes.

Paste this message into your chosen tool:

In this folder, create a simple web page in a single index.html file, with the title “My first website”, a paragraph and a button that changes the background colour. Do not install packages or download resources. First explain what you are going to do. Then create it and open it so I can test it. Do not publish anything.

This is a suggested exercise. You can check the result without knowing how to code.

First read which files it intends to create and which commands it wants to run. If it uses words you do not understand, ask: “Explain what this action is for and what it will change.”

In Claude Manual, review the comparison of changes — the diff — before accepting them. In Codex, review the resulting files: Ask for approval does not stop at each edit inside the folder.

When a permission request appears, approve it only if it fits the task. If it proposes downloading tools or acting in another folder, reject it and ask it to return to the exercise. You do not need to memorise every button name: read the specific action you are authorising.

If it cannot open the page, ask for the path to index.html and open it in your browser. Check three things: the title appears, the paragraph is readable and the button changes the background. Then request a small change: “Change the title to ‘I’m already building’.” Check again.

Three easy mistakes to avoid

Choosing the wrong folder. Check its name before sending the message. For this exercise, use the empty folder.

Granting every permission on day one. Start with the recommended modes and understand each request before increasing autonomy.

Continuing to make changes without saving a working version. Before changes pile up, consult the step on keeping versions in the introductory article. It is the starting point for the future second instalment.

You now have a first page and a way to direct the work: explain, review, authorise when appropriate and check the result.