This assumes you have already installed git on the system in use.
Creating a new repository with git is very simple. First, using your favorite command line tool, navigate to the directory you want to start using with git. Then, it’s as simple as
git init
You could also navigate to the parent directory, and
git init
so, something like
git init my-new-project
And now you have a new directory called my-new-project that is under version control with git.