A complete beginner's course

Build your first useful app with Codex

Create and publish a personal task-list website—one small, checked step at a time.

Overall learning outcomes

By the end of this course, you will be able to:

• describe a simple software idea to Codex in plain English;
• build an app through small, checked changes instead of trying to do everything at once;
• create a website with a task box, add button, finished tasks, remove buttons, and remembered tasks;
• test an app before sharing it;
• understand the sharing options available in their Codex setup; and
• publish a working first version of an app.

Who this course is for

This course is for people who have never programmed before and want a calm, guided first experience building software with Codex. It suits learners who are happy to type instructions, look at a browser page, and take one small step at a time.

Who this course is not for

This is not a course for someone who wants to learn to write code by hand, build a complex business system, make a mobile app for an app store, or create a task list shared and synchronised across many people and devices. Those are good future goals, but they need more tools and concepts than this first course.

Before You Begin

You need a Windows or Mac computer, a ChatGPT account with access to Codex, an internet connection, and a modern web browser. Chrome, Edge, Safari, and Firefox are all suitable if they are already installed on your computer. You also need about two and a half hours to complete the course, plus any extra time you choose to spend fixing small problems.

Open the ChatGPT desktop app and switch to Codex. Some Codex features, including the ways a website can be shared, may depend on your account or workplace settings. That is normal. This course shows you how to ask Codex what is available before you publish anything.

Codex may occasionally show a permission prompt. This is a small message asking whether it may do something such as create files, use a folder, or run a local website preview. Read the message before choosing. Approve it only when it matches the step you asked Codex to do. If it does not match, choose Cancel and ask Codex to explain.

You will use a local preview before publishing. This is a version of your website that opens in your browser on your own computer. It is not public and other people cannot open it yet.

How to get the most from this course

Treat this course like learning to cook a new recipe: complete the current step, check the result, and only then continue. Do not skip ahead, even when a later feature sounds more exciting. Each module prepares the ground for the next one.

Use the same pattern every time: Ask → check → approve → continue. Ask Codex for one small change. Check the page in your browser. Tell Codex whether it worked. Then move on. If something looks wrong, say what you see, what you expected, and ask Codex to fix just that one problem.

You do not need perfect instructions or technical words. “The button is missing” is a useful instruction. Keep a small note of anything that does not work, and use the troubleshooting checklist when you need it. Most importantly, do not move to the next module until the current module's checklist is complete.

A course-wide recovery rule

If Codex's instructions differ from this course, pause. Follow the safe, smaller action first and tell Codex exactly what differs:

This course says I should see [expected result], but your instruction says [what Codex said]. Please explain the difference in plain English and give me one safe next step.

Your browser check is the final check. Codex can review the work and suggest tests, but you decide whether the page works by opening and using it yourself.