Meet Codex and Open Your First Practice Project

What Codex does

Codex is OpenAI's coding agent: you describe a task, and it can inspect project files, propose or make changes and run checks using the tools and permissions available to it. You can ask it to explain a project before asking it to change anything.

You do not need to write code from scratch to follow this course. You will work on a small HTML, CSS and JavaScript page, learn what those files do and check the result in a browser. Understanding the brief and inspecting the finished work are part of the job, even when Codex writes the code.

This course is free to read. Codex access and usage are separate: check your account, workspace rules and OpenAI's current pricing and availability. You do not need to create an API key for our desktop practice route.

Choose one place to start

The official quickstart covers current setup. For this course, use a local folder in the desktop app. OpenAI's current documentation calls it the ChatGPT desktop app and describes a Codex choice within it; labels can differ across installed versions. Use the official download and installation instructions for your operating system, sign in and choose Codex when that choice is shown.

Other surfaces exist. The Codex CLI runs in a terminal; the IDE extension runs beside files in a code editor. Cloud work uses a configured remote environment. You can learn those later. Pick one surface for this first project so you know which files you are working on.

Get the starter files

Download the Codex starter project and extract it into a new folder called codex-practice. Keep the ZIP unchanged as your starting copy. Open or add that local folder as a project in Codex, then start a new chat inside it.

The official projects guide distinguishes local folders from projects that use uploaded or connected sources. Check the selected location: a similarly named chat does not establish access to the folder you intended.

The folder contains a fictional workshop page and its instructions. No client records, login details or paid service are needed. The page has one deliberately incomplete button behaviour for a later debugging exercise; the README tells you what to expect.

I am learning Codex with this fictional practice project.
Confirm the folder you are working in and list its top-level files.
Read README.md, SOURCE.md and AGENTS.md.
Explain the purpose of the project in plain English. Do not edit files or install anything yet.

Expected result: Codex identifies the practice folder and six files, explains that it is a static workshop page and notes the intentional button issue. If it cannot see those files, fix the project location before continuing. Do not accept a guessed description as evidence that the right folder is open.

Keep the course workbook beside you for task briefs and check results. You can also complete the lessons by reading the examples if you cannot access Codex yet.