No offense, but if you have to ask that question you're not ready to take prohormones. You should only take them:
1. Once you've reached your natural muscular growth potential
2. Once you've reached your natural skeletal growth potential (after your growth plates fuse)
3. If you're at least 20-21
4. If your diet and routine are perfect
5. After you've done at least a few months of research
I would advise you not to take them, but if you're going to anyway, at least do some research on them. Go
here , it's a start.