Gaining muscle would only be possible by working out and taking enough amount of proteins.
Whenever we lift weights in gym our muscle breaks because of load. Post workout we have to take enough amount of proteins in a diet. The proteins you intake should be the amount of weight of your body.
E.g 50kg boy should take a minimum of 50g protein daily if he is doing any physical work.
The beauty is that your muscle doesn't grow after eating and it does while sleeping. While sleeping you brain rebuilds the broken muscle in such a way that it could lift weights more than you did in past i.e it makes your muscle stronger.

In order to grow your muscle naturally consume proteins in natural way(Eggs,Dal,Rava etc..). Consuming Protein powders is the artificial way.
You could gain muscle faster by using protein powders but there are side effects.