To target your butt and thighs, try a combination of exercises, including the star lunge, the locust (from yoga), and squeeze squats.
Star lunge: Stand with your feet shoulder-width apart with your hands on your hip (or holding light weights). Looking straight ahead, lunge straight out in front of you (the 12 o'clock position) with your right foot so your thigh comes parallel to the ground, but your knee does not extend past your toes. Your left knee should nearly touch the ground. Next, lunge to 2 o'clock, then backward to 4 o'clock and 6 o'clock. Continue the lunge pattern, starting with your left leg to 6 o'clock, then around to 8, 10, and finish with twelve o'clock.
The locust (from yoga): Lie on your stomach on the floor. Raise your legs straight behind you as high as you can without putting excess strain on your back. You can do both legs simultaneously or one leg at a time. Hold the position and repeat. Also try the star lunge and squeeze squats.
Squeeze squats: Hold a medicine ball (or beach ball or basketball) in between your lower thighs. With your hands on your hips or out in front of you, squat down, keeping the ball in place and not allowing your thighs to go further down than parallel to the floor. Come back up. This works your legs, butt, and is great for developing balance.
Find out more about this book:You: Being Beautiful - The Owner's Manual to Inner and Outer Beauty