my weight scares me and I need to know how to lose some

I'm 14, my height is 4'11-5' and I'm about 150 lbs, my weight scares me and I need to know how to lose some. I'm mostly worried about my thighs, they are extremely large. My mom says it's just muscle but I haven't played softball for a few years now. Am I overweight? If so how can I drop some pounds?