Regardless of age, roids need close attention for it to be safe. At 19, it's highly unrecommended as you can still grow and it'll screw up your natural growth hormones.

Honestly, this isn't something to discuss lightly in a forum.

Judging from your initial post (the fact that you're asking about creatine, protein shakes etc.) clearly shows that you're still a relative beginner to bodybuilding.

I STRONGLY advice against going roids until you've exhausted other natural means of getting big.

You'll need A LOT of technical and medical knowledge to user roids relatively safely, based on your post, you still need to learn about basic body building dieting and such.

I'm not against roid use, but don't be foolish enough to think that you can gain so much without losing just as much (if not more) - healthwise.

Craploads of info in my other site, you might want to read up. http://pbfb.co.nr/