Good advice from Billy as always.
Understand first that before you even consider a cycle I can tell your diet needs tweaking. For a person who has never ate sufficient calories, a diet in itself can be almost like a AS cycle. For a skinny person such as yourself, your calories are needed to pack on the mass as well as carbs, If your not taking in enough calories and carbs to add bodyfat weight, then your body turns elsewhere to burn..where else to go but your muscle? So in short there is no one important thing in someone trying to add mass bro..I know I use to be skinny, take a look
http://briefcase.yahoo.com/abercrombie_pimp21
Though I am not the biggest guy I have come a long way and faced a few battles to get here.
So take in calories and carbs along with alot of protein, this way your body burns the extra to fat to build extra muscle instead of burning muscle to try and build muscle.
Hope this helps