Losing weight over summer, please help me lose these pounds? I'm a really big 15 year old girl?

im 5'7 and 204.7 pounds and me and my boyfriend where planning on working out for the summer, him with his friends and in all alone haha, so if you want we can be work out pals, email me if you are intrested, is it ok that im 20? loving_peace10@yahoo.com