Is this unhealthy?! and suggestions for a diet.....?

i am 11, in 5th grade, entering 6th. i currently weigh around 110lbs and is 5'2". i have belly fat and am not skinny, but not obese or obviously fat, but a little chubby in the body. im trying to go on a diet, what should the diet be? im trying to lay off the junk food, get more exercise and eat more fruits and veggies. wat do u think? also, im not having any cookies at lunch anymore or doritos. instead im having no dessert, but if i do it would be one of those 100 calorie bars. but i do have sunchips and a sandwich and water.