so on the skinny side. you'll need to eat more often, like every 3 hours if possible...5-7 times a day basically. Also, more food. You'll eat these 5-7 small meals constantly to keep your metabolism and energy up, as well as fuel the body with protein so your workouts can pack on muscle.
i would browse the other threads for diet ideas....just cuz we cover the basics all the time.
as for exercises, stick to full body workouts, 2-3 times a week. Mostly compound exercises...bench press, pull ups, rowing, squats, deadlifts, shoulder presses, and then just a few curls, tricep extensions and calf raises. don't forget abs either.