Hey Imoutthere,
First let me commend you for taking the time to ask for help and not just jumping on the first supplement/steroid you were recommended.
That said, I have to agree with jomi822...your training and/or diet must be off. My bet is it has to do mostly with diet, as that's most peoples problem in my experience.
I've had countless new clients come to me, expressing the exact same problem you are, saying "They can't gain weight/muscle no matter how much they eat". 100% of the time, I've found that once we broke down EXACTLY what they were eating everyday (HONESTLY), and when, we identified the problem, made changes to their diet and, like magic, the muscle appeared. (those that actually followed the new diet that is)
The truth is, it's physically impossible for the body to intake more calories than it burns and not put on weight. The trick is finding out how many calories your burn per day, on average, and then eating that many + about 10-30% depending on your goals. You also have to be sure your eating the proper macro nutrients and the right times, otherwise you'll simple be putting on fat and end up with the exact opposite problem from what your experiencing currently.
As recommended above, post your current typical diet and exercise program (as detailed as possible) and lets see if we can't pin down the problem. Remember,
be honest with yourself...
don't post what you TRY to eat everyday, post what you ACTUALLY eat everyday. Otherwise this will just be counterproductive.
I can recommend some supplements, etc...but first lets build a strong foundation.
If that's not there, all the supplements/steriods in the world won't help...at least not in the long run.
Workin