Any apps or suggestions for diet/weight loss?

Hi guys so right now I am currently 5'4 and weigh 137 pounds. I am looking to lose weight to go down to at least 120.  I am very far from fat but I do have belly fat that I would like to get rid of. I was just wondering if anybody knew of any apps for iPhones of workouts that will help me reach my goals and take away some stomach fat that I don't want or know of any diet plans to go on? I am currently a member at the gym but id like some guidance of exercises Thanks guys! Please no rude comments(: