Question: How do I sign-up up a Games for Windows-LIVE account?
Answer: If you don't have a Games for Windows-LIVE account you will want to sign up for one in order to play multiplayer and unlock achievements in the single player game.
Sign up for an account now here: http://go.microsoft.com/fwlink/?LinkID=76017
If you need a detailed walkthrough on how to sign up for Games for Windows-LIVE, you can read ours, found at the following link:
Walkthrough for Games for Windows LIVE Sign Up