There are also several clients to help make things easier. For instance, Github's own https://desktop.github.com is pretty good. There are also plugins for Git(hub) in Godot, but I have no idea how well they work.
But basically, you'll probably want a one-one relationship between your projects and your git projects. If you have multiple projects, you may want to have separate projects for shared code/ resources, and if you work on a project with multiple people, or regularly have sprints where you try something completely different you aren't sure is going to work (and hence you might abandon), branches would be worth learning about, but I wouldn't worry about that stuff if you're just starting out.
It's going to take some learning. As we develop Free Software, at GDQuest, we use Git. I don't have a lot of experience with other version control system. Note that Git can get quite complex as it's designed to support really big international software projects.
Atlassian has great resources to learn git, explaining what version control is, how git works, and how to do specific things: https://www.atlassian.com/git/tutorials