This page contains links to good (external) tutorials and some more advanced features that you may want to read up on.

1. For something visual: https://learngitbranching.js.org/
2. For a very complete reference guide: https://git-scm.com/
3. Atlassian is always good for this stuff: https://www.atlassian.com/git/tutorials

For those working on very active repositories or any admins who lead software-based subsystems, you will want to look into the following additional things (just google "git " and pick your way through the results -- you're on your own to explore now.

1. Gitignore files
2. Rebasing
3. Git log files
4. Git diff
5. Git submodules