How could I make a boy fall in love with me?

My opinion on this situation would be that, in the first place if he rejected you that obliviously means that he doesn't like you. I would advise asking if he still wanted to be friends and maybe he'll grow into liking you. Trust me at this age don't call it love, I'm guessing by the way you said he was a boy that you are still pretty young, so for now I would try to grow into liking him!! Also I would make sure that you are very fond of this person before you just decide that he's cute and go all for him. Give it time and get to know each other!!