The place you'll want to go to register your code I'm pretty sure is the Mogstation, where you manage your subscription and access to different parts of FFXIV. https://secure.square-enix.com/accou...est=mogstation Try going there, inside there should be a place to activate your code. It's been a while since I did it myself, so my memory is a little fuzzy on it. You may also be able to register when you're launching the game and it is asking you to sign in with your SE account or create one.

Also I'll move the thread to the create forum.