Batman Gotham Night

I recently bought Batman Arkham City and recieved a code with it to stream Gotham Night but I can't seem to figure out where and how to redeem the code. So I was wondering if any of you could help me out. Thanks in advance.

Oh damn lol thanks I should have thought of that. The dude at gamestop told me I had to go on the Gamestop website to redeem it and I had the hardest time trying to find it on the site.