There is a really good getting started guide in the Git main site: 

http://git-scm.com/book/en/Getting-Started-First-Time-Git-Setup

You should at least define your identity (name and email address) because this information will be attached to the entries created into the version control repository.

So just fire up the Git Bash terminal.

And enter commands according to the example below.

$ git config --global user.name "John Doe"
$ git config --global user.email johndoe@example.com

You can use the –list option to check the options:

$ git config --list

That should be enough to continue.