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.
If you haven't already, you need to give up all sodas, candies, cookies, cakes, chips and other high fat, high salt foods. Limit or eliminate anything with white sugar, flour, potatoes, etc.
Opt for high protein things like dairy, lean meats, fish, etc and high fiber foods like veggies, fruits and whole grains.
Have you talked with your parents about your diet?
Unfortunately to lose 35 pounds before June is impossible. Try to aim at losing 2 pounds per week, you would lose 16 pounds !
Exercises- walking briskly, jogging a small amount of running, too much running can be bad for you and your bones as your still young and developing. Horse-riding, swimming, karate. even like using a skipping rope or trampolining half an hour a day can make a difference.
I would also recommend cutting out or reducing sugary and yummy foods, this will include fizzy drinks, sweets, chocolate, cake, biscuits, crisps.