Codeberg uses git too, so a lot of what you would have done with GitHub will still work.
Pretty much any git tutorial will serve you well, it's (mostly) all the same commands regardless of whether your project is game development or a fantasy novel.
Some resource suggestions:
- https://gitimmersion.com/ nice guided tutorial that takes you through the most common concepts of git
- https://git-scm.com/learn a bunch of educational materials here
The only real difference in game development might be if you end up with super large files (some blender files, certain assets, etc) then you can look into git-lfs as well. https://git-lfs.com/ That's not always necessary, and it can be added later on, so you don't need to worry about it until you need it.