It's not a very simple task although.. You essentially receive a "Promo Code" that acts as $15 off coupon in the checkout process. Then you proceed by waiting forever for it to actually show in both your games section and order history...Too many hands in the cookie jar if you ask me
Mine went through a short while ago. Not sure if anyone else has had the same luck?
Took forever for it to show up in "My Games" section but I was currently downloading it until I got a Windows Activation error