How can I lose weight over the summer?

I'm 13 (almost 14). I'm 5'3". 155 lbs. My goal is to reach at least 120 lbs by August 22ish. idk when school starts. but by the first day. I want to look trimmed up by high school :) I have decided to not drink soda. only once in a while. but I don't drink that much soda anyways. I walk in the mornings. I'm going to do cardio in the afternoons, and dance crazy while listening to music haha. I really need more help and tips. so please help! Current: 155 pounds. Goal: 120 pounds Goal Date: first day back at school