And brakes. Besides that, ride lots. Pick an event (doesn't have to be a year from now) that has a reputation for good support and a reasonable route and go for it. Most organized rides I've been on have a lower age limit; riders younger than that need to have an adult with them. Check the registration info for specifics on your event when you pick one.

Many bike shops and clubs have youth programs to help teen riders get into the sport. Ask around. Welcome to the ride!