User blog comment:Commdor/ME3 Demo Arriving January 2012/@comment-4118072-20111209155830/@comment-1221773-20111209194552

What platform did you get it for? If it's Xbox 360, it should just be a matter of entering the Online Pass code into the "Redeem Code" tool in the guide menu, then starting up Battlefield 3 and signing in with your EA account.