Who doesn't want to gain muscle fast? It can be done, but it all depends on proper muscle training and following a healthy diet and proper muscle building exercises.
Here is how you can gain muscle fast:
Just 10
Don't do more than 10 repetitions when lifting weights. Especially if you are skinny, by the time you reach the 11th repetition you are basically wasting your time because this won't help you gain muscle faster.
Focus on one muscle per day
That pretty much says it all, split up your workout during the week to target different muscles, chest, arms, back, legs etc.
Keep Track
Keep track of how much you are lifting and slowly increase the weight you are lifting every 2 weeks. Many guys forget about this and just keep on lifting the same amount for months.
It is important you don't over train yourself or fall into thinking that the more you lift or workout the better. That is wrong. Remember to focus on one muscle per day and keep your workouts short. Have a stop watch nearby to keep track of how long you are working out and resting.