Do some exercises that target your butt muscles:
Lunges (Stand with one leg forward and one leg back, Slowly bend the knees, keep your self straight, go back up)
Reverse leg raises (lie face down on your bed, with only the upper half of your body, lift your legs up so that you are parallel on the ground)
Scissor kicks (Lie down on your back, lift one leg up at a 45 degree angle, put it down while raising the other leg, then do it again)
Squats (Stand with feet shoulder-width apart, Slowly lower your body until your thighs are parallel with the ground, go back up)
Take note that you have to go do some cardio too. This will burn some of the fat off your butt and make those butt muscles look more prominent.
For breasts, I suggest doing good old push ups. If it gets boring, there are a lot of push ups variations you can do.