Supplements have their uses in bodybuilding but the people who get the most benefit from the sales of the products are the companies that make them ...
not you.
To go from skinny to muscle man you need to pay attention to your genetics and how they work before you simply hit the gym and chug down loads of useless weight gain supplements because there is a faster, better and easier way that simply involves a few changes to the way you have been doing things.
Firstly you need to realize that you have to eat, exercise and rest differently from the other guys at the gym with less skinny genetics that you because this is what makes it difficult for you to gain muscle.
It comes down to your metabolism which is much higher than other people and is the part of you that keeps you skinny by burning through energy so fast there is nothing left to go to fat; it also means there is nothing left to feed the muscles.
So what do you need to change to go from skinny to muscle? Simply put you need to:

• Eat more calories to overcome your fast metabolism and have energy and nutrients left to feed the muscle.
  
• Lift heavier weights not do more repetitions and only high stress on muscles will cause your body to react and grow the muscles to adapt.
  
• Rest enough to give your body time and energy to repair and grow these muscles or you will waste your gym sessions.