FastForYa, I started lifting when I was 14-15 and I will be 16 in May and I just started taking the suppliments. If you want to gain some weight, I took the GNC Weight Gainer 2200 Gold. It has everything you need, 2000+ calories, I think 50g of protein, creatine in it, amino acids, it has everything you need. But like Prince said, you need 1g of protein per pound, so just take one in the morning, after your workout and before bed and you should be fine, and remember to eat right. Hope I helped you out.
p.s. I wanted to do the same thing, just lift to get some muscle, but once you start lifting you get a "rush" and you'll soon want to lift because you like it. That's probably how everyone here started. Good luck.