This boy i like.Can you tell me how to make him like me or any thing to do with it?

okay i like this boy and he is really nice, but i thought he liked me cause he asked me to go see a movie with him.But then whenever my sister who i can say is prettier comes around he follows her around . I'm 14 he's 15 and she's 16. i really really like him so please be nice.dont say any thing your gramma wouldnt say unlesss she is a biker .