It sounds a bit plain and boring, but if you're just wanting to learn the basics of C# then you could refer to the official Microsoft docs:
They're quite basic, but do offer some fundamental knowledge. If you're after more theory such as architectural patterns, I'd say you're better off looking at resources that are language-independent
This led me down a real rabbit hole of looking at what you can do with git commands, very neat.
There's a few more things you can do which I found, like switching to the Nth branch you last had checked out: https://www.w3docs.com/snippets/git/how-to-checkout-the-previous-branch.html