No worries man, we can help you out.
If you bought the game digitally, then you would have gotten an email with your registration number (the download number you are referring to). In that email it should also mention our downloading program, Impulse.
You'll need to download Impulse (its free), and then it'll allow you to register games and download them. You can also use it to keep your registered games current with the latest free updates. Here's the link to the impulse website (http://impulsedriven.com/about.aspx).
Let us know if you need any direction.
