help with weight training and weight loss?

i am 17, i want to lose some weight in my lower body (legs and butt) and chest etc… im not fat, i just have abit of body fat on me. how long would it take to see results if i did treadmill every second day (8-12km 2% incline) (20 mins which burns 400-500 calories every session on the treadmill) and i eat pretty balanced diet. i dont eat sweets or nothing like that.
i play tennis 3 times per week and soccer once a week, as well as school sports, pretty active. any other tips with related topics??
i do weights 3 times a week, pretty light though. 10kg dumbell and 20kg bench (with the 2 dumbbells)
remember im only 17 and i cant do everything that adults do!
thank you!

also what is the best way to burn stored fat???