You own 1-star stickers by default, while 2-star stickers will have a description of what you have to do to unlock them. 3-star stickers will display a hint about how to unlock them - you'll have to do some experimenting! Secret stickers (4 and 5-star) do not unlock immediately, as they have a timer. They are designed that way to keep them secret, but do your best to discover how to unlock them and then share your methods!