How do i beat up a bully so she'll leave me alone and stop getting ppl to cirlcle around me and grab me?

Hi, i'm in six grade. I need to know how to stop a bully from hurting my feelings and harrasing. She is about my age. Were in the same grade. She is so mean. One day on the playground/hangout area she got a group of kids, about 40 of them in are grade then they circled around me and grabbed my arms so i would run away. Finally everone was saying boo and stuff. I was to afraid to break away. I was think about cursing off. But i'm only in 6th grade. Then they pushed me and hit me to the ground. A teacher came out and yelled at them. Then Fiona, the girl that bullys people showed up with here 2 (bodygaurds) and screamed at me! What should i do to make her go away? Thanks.