I already told my principal. She said she is going to handle it but, she hasn't done any thing to help. Should I just leave it alone or fight him and get in trouble?

When someone is picking on anyone, and it's uncalled for you should always try to stop it.
And when I say stop it I don't mean getting into a fight with the bully. Surely there's a teacher or some form of adult supervision nearby that can intercept. I'm sure your school have a bully policy of some sorts. Talk it out with your teacher, but do not do it alone, the people getting bullied should come along also.

So basically just find any adult at the school that handles child care, and have your group talk it over with the adult.

Don't fight him!

As the other poster has said, there must be a teacher supervising in the yard, go talk to them.

Just because you don't see your principal doing anything, does not mean they have ignored you, they could be monitering the situation.

Don't forget bullies usually have something going on themselves they need help with.