Get a good protein powder. Muscle Milk and Whey Protein are both awesome.
Basically, when you're done working out you want a protein heavy meal, and a protein shake gets that done fast. Also, when you're lifting weights, do A LOT of weight, very few reps, and about 5-6 sets. As an example, you might bench press 100lbs (just throwing out a number--just make sure it's a struggle--but not too much of a struggle), and lift it maybe five times, then take a break. Then do it five more times, then take a break. Do this about five times.
TL;DR: Protein shake after workouts, high weight, low reps, high sets.
Edit: As always drink lots of water and try to cut out fatty foods. Get a workout journal to keep track of your progress, and give yourself small, but satisfying rewards at key benchmarks to keep you motivated.