Protein Powder wont do a damn thing for you. The number one thing to do is work out; if you increase your caloric intake without working out you'll gain weight but it won't be "quality" weight.
1. Work out
2. Eat beef, chicken, whole weat pasta, sweet potatoes, oat meal, and fruits and veggies.
3. Have 2 or 3 protein shakes a day at most BUT do not use them to substitute a real meal.
4. Get plenty of rest.
That's it.. There is not magic trick to it, no magical powders; even steroids won't do a fucking thing unless you follow the steps. The above it what will get you some size.
Space Gray 2011 335xi E92
Old: Jet Black 2007 E90 (with xenons
and modded) 328i