Let them know that you want to lose weight
and enlist help in
choosing the proper foods/amounts.
Since you are so young, you need to good balance of nutrients in order to be healthy.
Figure out how many pounds you need to lose, then calculate your needed calories.
As a general rule, you should stick with lots of veggies and whole fruits mostly, along with lean protein, at least 3 servings/day of dairy, and stick with whole grains for breads, cereal, etc.