Unfortunately, it's a bit too late to lose 35 pounds before June. Any type of exercise is good for you....... you could try walking, yoga, biking, swimming, dance, tennis...... anything is good.
You have to watch your diet, as well as exercise. According to your profile, you're only 15, so at that age, your body is not fully developed. You have to be very careful losing weight or you could have trouble later in life.