Ok. So I logged into steam. Saw the little + below all my steam games that said, "add game to steam" I then clicked it, it asked me for serial code I pasted in my gamestop serial code. It processed it and found it and is now downloading and installing.
It's like... Buying a FORD and being told you have to walk to the KIA dealership to pick up your new car. That makes no f*cking sense at all.
If you are going to distribute your product like a marketing heavy company have the common sense to list proper directions for people to get it. I'm hoping the gaming experience is better than the installing!
Thanks Island Dog for the great hints.