Playing the Ball Bounce game and the Apple-Picking game will gives your ponies shards of a star, once they have a complete one, they can play the Magic Wings game to earn the star.  Ponies with more stars can manage higher level positions in shops, which will earn more bits over a longer period of time.

Higher level stars require more "score" (earned from the minigames) to complete a star.  Also, ponies who cost more to welcome to Ponyville will require more "score" to earn ever the first or second star.