You should not use steroids until you are at least 23 years old. You are way too young for steroids. Up until the age of 23, you are still going through puberty. Throwing steroids into the mix at that time will prevent you from properly going through puberty.
I started steroids at 18 and it was the worst decision I ever made. Learn from my mistakes.
Are you trying to build muscle? At 17, your body is already primed to grow. You are young and your natural testosterone levels are through the roof. All you need to do is eat a high protein diet and train with weights HARD 4-5 days per week. If you want to supplement with something, buy a good quality protein powder like isolation from n2bm.com to help meet your body's daily protein requirements.
Are you trying to cut? Steroids do not burn body fat. They increase muscle protein synthesis and prevent muscle catabolism. I feel like I am beating a dead horse saying this over and over but it's a very common misconception and something a lot of people get wrong. Bodybuilders commonly include steroids into their pre-contest cycles to prevent muscle loss when dieting on low calories and doing lots of cardio. The steroids themselves do not burn body fat.
If you want to loose body fat - You need to perfect your diet and training. Its as simple as that. Fat is basically stored energy. To burn fat, you need to expend more calories then you consume.
Here is a good article for you to read on how to set up a carb cycling diet for fat loss:
http://www.evolutionary.org/cycling-carbohydrates
If you are adamant on supplementing with something, look into cardarine. It will do way more for fat burning then any steroid ever will and it is non hormonal.
http://www.evolutionary.org/cardarine/