How do i lose weight?

I was born with asthma. My mom told me once that the inhalers I was prescribed had steroids in them and gave me bad hair breakage and made me gain weight. I am currently using a Xopenex fast-acting inhaler but I don't think it has steroids. Since I started gaining weight I haven't been able to lose any. I've tried dieting. I was a cheerleader in middle school and high school for exercise, but it didn't work. I've been told that most of my weight is muscle but I still want to get it off. Any insight or suggestions? If you have any expertise, please share.