Consult a nutritionist. Everyone has a different metabolism and will require slightly different supplementary nutrition for building muscle. It's a good idea to meet at least once with a nutritionist or other health counselor to build a diet plan specifically tailored to your body and what you want to do with it. It's impossible to give a single, generalized diet plan that will work for everyone, so you'll need one specific to your needs.
You can stick to natural supplementation with things like a protein powder and creatine if you're looking for faster gains. Now don't think I mean faster like 10x faster, I just mean slightly faster, but usually worth it for the cost. But don't go overboard on supplements either. A few basics should do. I recommend a protein, creatine, EFA's (essential fatty acids), a multivitamin, and amino acids. Once you become more experienced a pre-workout N.O. product could be a valuable addition as well.
One of the most misunderstood areas for new bodybuilders is nutrition. I talk to guys all the time that have no idea of their daily calorie intake, their daily protein intake, their carbohydrate intake. They have no idea of what types of foods they should be eating, or when they should be eating them. They don't know what supplements do what and what they should using. Let me refer readers to some of my other articles that detail these areas.