Print out your certificate and head to the designated window as early as possible on your birthday. Present your certificate and your ID and you can choose between the free admission, fun card and fast pass. As an annual pass holder I chose the fast pass, and it was a total BUST. They only allow you so many fastpasses and it's only for cartain rides. Once you hit your limit, you don't get anymore birthday fastpasses. Unfortunately, we found this out WAY too late and as the Magic Kingdom got busy, we were out of fast passes. This was during President's week and didn't exactly make for the best birthday. If you get the fun card, you can't use it to pay for food, only merchandise and only in certain strores. Go with the free admission - it is the ONLY offer that's truly worth it!