I have great game , etc , only thing i believe im missing is serious upper body gains.

I play soccer so im pretty fit , i have a lean body 5ft11 , 70kg , however i literally cannot put any meat / muscle on my arms and upper body , my legs on the other hand is way easier.

I spoke to a friend and he recommend that i take SERIOUS MUSCLE MASS , when i start lifting ? any thoughts on this because i read that it is rather unhealthy and can lead to me becoming fat?

Also what gains can i make in 2 months im planning on hitting gym 3 times a week , bench , curl etc , and soccer for running.

Another friend said instead of any serious mass proteins i should focus on eating alot like double to amount i currently eat? i doubt its physically possible ?

Any thoughts guys ? all input is appreciated