How does an athletic teenage girl stay healthy but lose weight?

im 14 about 5' 6'' and weigh 126 pounds. I play basketball, volleyball, and run on a weekly basis to try and stay healthy. i could probably be a little thinner around the middle section. What can i do to lose the extra weight but stay healthy why im doing it. I know i need those carbs and calories and things like that but what do i need to eat and how much do i need to eat to stay healthy and loe weight, PLEASE HELP ME IM LOST!!!