Git is a program for managing different versions of codebases. It's main feature is being able to commit code changes to a main branch, while allowing you to switch back to older committed versions. It also has support for branches off of the main one, allowing separate development of different features / changes, and then a merging feature to merge different branches into each other.
GitHub is a server for Git repositories. It comes with useful features such as pull requests (a request for someone else's branch off of your code to be merged back into it), issues (bug reports / feature requests), and other features to manage your Git repository with a GUI.
I'm a terminal fan, so I use commands rather than the vscode ui to manage git. Stage all changes with `git add .`, then commit with `git commit`. Add a good message in the text editor, save and close the file, then push to GitHub with `git push`.