Teen girl wanted to lose belly fat.what are best exercises?& any other suggestions please.?

i have started drinking a lot more water,so far 5 bottles(small). will drinking more water help me to lose weight? i have cut down on food a lot.i eat a healthy breakfast and dinner.i'm never hungry at lunch time so i drink water to substitute. i have been told that doing sit ups will help flatten my stomach but i have researched it and have found that they dont get rid of belly fat :/