How do i tone up my stomach?

my weight is average im 13. 5 ft tall + about 125 lbs. but I hate my stomach. I always feel like I look fat. as long as im healthy the number on the scale doesn't really matter, I just want to look thinner.
how do I make my stomach smaller + flatter ?

abdominal workoutss and running

maybe try using something around your waist to make it sweat more when your working out...my friends say it works.

doing situps/crunches will only tighten your stomach and build up muscle.

To burn fat you need to do aerobic exercise, such as running, cycling, etc

yup Running will do it .
try atleast 15-20 min a day or even swimming.