If you look in the top left corner of this lesson, you should find a blue button that says "Course Resources". Click on it to download the starting files for the Simon Game Challenge. Unzip the downloaded folder and drag your project into Atom.

https://www.appbrewery.co/p/web-development-course-resources

Once you've opened up the project, take a look around and orientate yourself. There is a sounds folder containing the UI sounds for all four buttons, there's also an index.html file that has four buttons pre-styled with CSS. You can check out what it looks like by copying the full path of the index.html and pasting it into Chrome.

In the next few lessons, there are step by step challenges to build the functionality of this game.