I'm getting constantly made fun of by other kids in my school and I can't handle it! What can I do to stop it?

So its my first time in an American school and I totally hate it because everybody makes fun of me and this really annoying girl keeps picking on me and some snobbish girls keep annoying me and a few girls ignore me. I've laughed all this off till now but I just can't handle it anymore!! Please give me a few tips on what I can do to stop all this!