Most women are obsessed with building nice solid and shapely buns. The butt muscle is commonly referred to as the glutes. It gets this name from the three muscles that it consists of: the gluteus maximus, gluteus medius, and the gluteus minimus. Logic will tell you that the gluteus maximus is the largest of the three. It's the one that's most noticeable.
The gluteus medius and minimus are located around the body part of your pelvis, so they are not as apparent.
Traditional Squats
The squat is a compound exercise (works all the muscles simultaneously in that muscle group) and top-class for adding shape to your bottom. Include this exercise first in your bun training to ensure you target the entire glute muscle simultaneously.
Use a variety of rep ranges and sets. It's safest to squat until your upper legs (from knee to hip) are parallel to the floor. However, at times you can squat past parallel, provided the poundage you use is light. Also, with light poundage you can vary foot placement and foot width to further target other areas of the upper legs.
Pile Squats
Further extend the traditional squat by adding pile squats to your program. Pile squats can add some variety and help target the muscles of the inner and outer thighs to a much greater degree.
If you are unfamiliar with the pile squats it's simply taking a wide-stance with your toes pointing outward. Hold a dumbbell in front of you and squat straight down and rise back in a controlled manner.