How to organize repository structure?

I am a new Gitlab user and new to GIT in general. Here is my situation. On my local drive, I have a folder hierarchy setup such as: Projects > Linux > Arch Basic Install, Projects > Linux → Arch KDE

I want to know, what folders would I initialize as a repo. The main Projects directory, the Linux sub directory or the sub directories under linux?

And, how would I establish a similar workflow on Gitlab? Would I have to create multiple repositories? How would I do this?

Thanks in advance,