you wont get any gains if your diet isnt in order. calculate how many calories you need on the calculator in the tools section in this site, then add 500 to that number since your trying to gain weight. read up on the articles and other threads on this site for an idea of what stuff to eat. you should follow roughly a 40/40/20 or 30/50/20 ratio of protein carbs and fat, meaning that if you eat 3000 calories a day, you should eat 225-300g protein, 300-375 carbs, and 67g fat a day. you should eat 5-7 meals through the day, once every 2-3 hours to keep your metabolism going.
i suggest joining a gym, but you dont have to.
heres a dumbbell and barbell based 3 day split
http://www.muscleandstrength.com/wor...e-workout.html