How do i put a hat in a gamepass?

i want to put a hat on the player when he/she buys a game pass.but how? (its a dominus frigidus)

http://wiki.roblox.com/index.php?title=API:Class/Player/CharacterAdded Here's something to get you started and if you make something and it doesn't work then come back, at least i'm pretty sure that's how all of this works.