At your age your hormonal system hasn't fully stopped developing yet and by shutting your natural testosterone down by using steroids it can have some serious side effects, in many guys testosterone wont reach peak or even worse case symptoms of low test which can have awful sides such as low libido, erections problems, mood swings, fat gain, muscle loss and depression to name a small few.

Please read these threads they will help you understand

http://forums.steroid.com/showthread...ids&highlight=


http://forums.steroid.com/showthread...-a-first-cycle


My advice is to reconsider your approach and concentrate on your diet and training and build a solid base, then in a few years you will be in a far better place to use steroids, best of luck