I'm soon 17 years old, 1,86 high, 72-73 kg. I have a problem gaining weight, I'm kind of skinny, pretty muscular though.

I'm looking for a steroid that's not too powerful, that fit's my needs. I want to grow bigger, as my muscles still stay marked. if i could take it orally it would be the definite best thing, but if injecting it is a better option i'd rather do that.

how much will it cost me?
should i consider taking smaller doses if i don't want the full effect?
anything especially i should look out for/do considering this steroid?
and most important, what steroid should i use?

Thanks