How should I gain weight, and turn into into more muscle?

I'm a male, 5'8", 125-130 lbs. I already work out, and i'm cut up. Now I want to gain weight, and turn it into muscle. This isn't as easy as eating for me. I gave up coca cola, and small sugary snacks to try and boost my weight gain to no avail. So the only soda like drink I drink is sprite. Now i'd like to get around 150-160 lbs by next summer if possible. I just need to know the best way to do it. What kind of protein, or whey gain should I take. How often should I take it for best results, etc.. If you know then please inform more. thank you