How do i build muscle mass?

Building muscle mass is dependent on what body type you are. Are you naturally skinny, muscular, or fat? If you are naturally skinny, then you will have to consume alot of calories to build muscle mass and workout 2-3 times a week, not everyday because workouts burn calories. Because skinny people(ectomorphs) have high metabolisms and burn off calories easily, they must eat lots to even think about building muscle. For them, high carbs and high protein intake is a necessity.

Now naturally muscular and fat people (mesomorphs and endomorphs) build muscle pretty easily from any kind of weight training. In order to see the muscle built, endomorphs must eat "clean" foods and leave the junk food out, raise healthy fat and protein intake, and possibly lower their carb intake. Mesomorphs are GODS blessed people. I say this because they can just about do anything or eat anything and look like Arnold. You've seen them before. These naturally muscular guys who don't lift weights.

As far as weight training goes, you can do 3 sets of 6-10 reps for each exercise for a bodypart to start out (beginner). Use one exercise for each part of the muscle being trained. As you progress, you can use more advanced set/rep schemes like 4x6, 5x5, 6x4, 6x6, 8x3. As long as your set/reps total at least 24. 24 is the least amount of reps/sets needed for hypertrophy (i.e. "Muscle Growth")

For chest, the chest has basically two parts to train, the upper chest and lower chest. You can use wide grip for presses and dips to hit the "outer" chest or narrow grip for "inner" chest. Incline presses and flyes for the upper chest, flat bench for middle and outer chest, and decline press and wide grip dips for lower out chest.

Be sure to use a weight that you can press can contract your chest at the top of the movement (i.e. "Sqeeze"). This is most important in developing any muscle being trained. It's not about how much weight is being used, but the contraction. And keep your elbows in close when pressing to avoid over use of the shoulders and get better contraction.

But to be honest, bench press is not even the best mass builder for chest, IMO wide and close grip dips are. Bench press is good for building strength by using heavy weight. It mainly builds front shoulders and triceps and some chest. Chest is mainly built from bench press when you are working the chest with contractions.