You can change your project's name and description on "Settings -> Edit project details", and see more options under that same menu. You can add a file using the "Files +" button, or add some assets via Glitch's CDN on "Assets".
If you want to learn more with videos, you can also check Glitch's "How-to" playlist.
Need help? Glitch has a friendly community for you to ask any question. Even rickrolls, trust me