desperate to lose weight

I just turned 14 three months ago. I'm 5'7 and weigh around 195. i want to get down to at least 120; i don't mind being a little more or less than that though. so, i would say in the 110-130 range. I am desperate to lose weight. I want it to be soon, but i am willing to take it slow but not too slow. I try diets, but i can never stick to them. I think i'm moderately active. i mean i don't exercise like for a specific amount of time every single day, and i'm not on any sport teams. i'm thinking about trying out this year when school starts, but i'm not that coordinated. but i'm willing to try. i like to dance and sing to the radio for like 30-45 minutes a day; i'm not sure because i don't really pay attention to the time. i have had this weight problem for about 5 years, and i really want to get rid of it. i'm tired of looking around at all of my skinny friends, never getting my size in clothes, and just being ashamed of myself! i want to be confident for once. Can someone please help?