Read Cy Wilsons article on Nutrition for Skinny Bastards.
In terms of supplements, I'd recommend Metabolic Drive Complete, Surge, Creatine, and BCAA's. Also, look into Omegazyme Digestive Enzymes from Garden of Life, they should help you out alot bulking.
I'm not sure what you're doing for training, but a good place to start would be Dan John's One Lift A Day program. Like he said, simple, but not easy. If you do that program for 3-4 months, put in a ton of effort, and eat the right way (which in your case is a ton of carbs, protien, and fat), you'll be on your way to 200 pounds.
Take it one step at a time, and realize the iron game isn't a sprint; you want to be in this for the long haul.