my friends say that he looks at my butt.
You want him to notice your personality before your butt for one. Also, don't go out of your way to much to be noticed. You don't want to look (or be) desperate or annoying. Find out what he likes. Learn about it so that you can talk to him. Find out where he goes and casually show up. Most importantly; don't ever change for someone. Be yourself. If they don't like you for who you are, they aren't the one.