For those of you still baffled by GitHub:
GitHub keeps your files in repositories (folders). Each repositiory can exist locally (on your computer) and remotely (on github.com). They keep in sync with each other.
So there are essentially two GitHubs, the main one is on the web at github.com where you are logged in. The other one is installed on your computer - GitHub Desktop. GitHub Desktop works like an extension of github.com, but running locally on your computer. It allows you to create local repositories and publish them to github.com later. It also allows you to clone remote repositories on github.com so that you have a local copy on your computer.
GitHub Desktop is doing the following with your local repository:
- tracking your files and showing you which files you have changed