On the most basic level only three things are necessary to build muscle: progressively heavy weights, enough food, and enough rest. I won’t waste your time so I’ll cut to the point: if you are looking to get as big as Jay Cutler then you are going to have to do steroids and train for decades.
If you are more realistic and only looking to get to a reasonable size in a reasonable period of time then this is entirely possible naturally. In order to be able to put on about 30 solid pounds of muscle, you are likely looking at training for a year to two years. Many people think that they have put much more muscle mass than they actually have because they have simply put on a lot of fat while they have bulked. They soon realised how little muscle they have put on when they have cut — but not before they have bragged to people forums about their amazing muscle gains.
Lifting progressively heavy weights means exactly what it says. You should regularly look to better the weight you have lifted last time around. This is the only way to build muscle. When you stop progressing with the amount of weight you are lifting your muscle gains will stop.
Providing you will lift heavy enough weights to force the muscles to grow you need to support new muscle growth by eating enough food. You need to enough food to put on a steady amount of weight but not balloon — as most of this will be fat.
You can count calories or you can just come portions of food. This is why following a set diet every day makes things easier.
If you notice that your weight gain has stopped then you need to eat more food it’s as simple as that. You need to take care that you are not putting on a lot of fat and that most of the new weight is coming from new lean muscle mass. You can do this with callipers to check body fat.
Most bodybuilding programmes will give you a few days off to rest. Rest you must or your muscles won’t have the energy to grow. You should definitely rest on your days off but you should also be sure you rest after you have finished training. The more rest and you can do when not training the better your results will be.