Yep another body question.. So will you answer it?

Ok so I am 14, 5"1 and I weigh 156.8lbs.. How can I lose weight? I feel so chubby.. Another thing I had to have like 4 back to back surgeries.. Which caused the weight gain. It also caused horrible stretch marks.. What do you suggest I do to lose weight and fade my stretch marks?? Oh and it can't be really strenuous.. I want to lose weight, have a flatter belly, and tone up my and thighs.. Please Please help me?