How the h311 do I kill Bowser?!!!?

Okay, I'm playing the Mario Brothers game for GBA, and I can't seem to kill Bowser! (Let me tell you first, this is the one where you are in Dinosaur land, and you have to save peach and all of the colored yoshi's, if this doesn't help, Bowser is in this giant flying thing with a propeller at the bottom. He throws his minions down, and he swoops over you). I can't jump on tho of him because he goes too fast and he is too high. What di I do? I have found all of the secret exits and switch palaces. By the way, I inished the special world on star road, but it just lead me back to the beginning, why? PLEASE HELP!!!!!!!