Start lifting weights if its possible for you to get a gym membership or whatever. Not only will you build muscle and look sexy(no homo but the more muscle you have, the faster your metabolism. Start watching what you eat too. If you drink soda, drop it, drop the junk food and any other crap stuff cause thats just empty calories. Try and get as much protein as possible. Carbs are important too. Start doing cardio in the morning. Look into HIIT(High Intensity Interval Training), perform HIIT 3 times a week. Eat a banana before HIIT sessions. The other 4 days I suggest doing fasted long duration(45 mins or so) medium intensity cardio. Start doing calisthenics if you cant access weights. That is, start doing crunches, pushups and pullups. And do not starve yourself, youll be catabolizing muscle and INCREASING body fat% if anything. Eat small but frequent meals. 6 times a day, 2 hrs in between. Have a cheat meal(fast food or something) once a week. And dont be stupid and wear a sweater while doing cardio or something, Ive seen ppl doing that saying that the more they sweat the more fat they will lose. Thats garbage, sweating will only cause you to lose water weight which will all be gained back once you rehydrate. Any questions, ask me

And oh yeah sign up on the bodybuilding.com forums, best thing youll do ever. And stay motivated, thats definately the most important part.