Eat lots of pasta, tuna and do some cardio.
Heres a little cheat :-) - do 500 situps with a blackback over your body (NOT OVER YOUR HEAD THOUGH!!), you will sweat badly, but dont take it off afterwards! As soon as your finished go on a treadmill for about 30 minutes. By that time you should be really sweaty. The more you sweat during a workout the more weight you loose.
BREATHING
Breath in through your mouth and out through your nose when jogging.
When doing the situps, as you sit up breath in through your mouth and out through your nose on your way down.
Check out my weightloss topic on how to loose bodyfat - you barely have any so don't worry too much.
If I was to advise you I'd say just build into that because soon youl want to put on weight to get bigger in muscle.
If your intrested in further help then pm me and I'll write you up a food list, a workout routine and a workout routine for your arms also ;-)
This message was directed at Toughened and once I have written the guides out I will publish them for the public.
Anyone can feel better about themselfs through bodybuilding - its a great sport.