How Can I Get A Beyonce Body?

Im a very slim female and i weigh around 107. Im very out of shape and i was wondering how could i gain weight and muscle to be more fuller. i want a beyonce booty and curves. My goal weight is about 115.Right now my body resembles a 13 year old boy. ): i'd like to add muscle in my calves, thighs and butt. I've tried exercising before but i never stick with it. Im also worried that if i exercising i will lose Weight which i want to avoid. what exercises can i do to get the body i want WITHOUT losing weight? How long will it take to see results? Also what types of food should i eat, how often , and how much. And lastly how much exercising should i do?