How to get started with muscle buildingThis is going to be a long answer so bear with me. Here I am assuming you are an absolute beginner. First things first, get a gym membership and a trainer, if possible.
Start with full body workout for a month with cardio on alternate days. The purpose of this will be to start off and accustom your body to a new regimen. Warm up and stretches are very important. Concentrate on form more than counts.
Slowly, move to a two day split (upper body and lower), then a three day split (pulling muscles on day one, pushing muscles on day two and legs and abs on day 3) and finally train one body part each day. Your cardio should also progress in intensity and there must be an increase in variety.
Things to remember are, your body will get used to the things you put it through so remember to switch it up. Another thing is, since you want to increase muscle mass heavier weights low reps is what you should stick to majority of time.
Get in a lot of protein for muscle growth. 1.5 g per pound body weight. Protein sources can be chicken, fish, eggs, soy etc.
Do not cut out fat entirely. This is a common mistake. Essential fats are required for body function and is not made by the body. Food is the only source.
Supplements are just that, supplements. They supplement your diet. Your diet is the key ingredient to achieve your goal. These will just give you the extra push when you can't make up for your macronutrients.
Other key things:
It takes time. Rome was not built in a day. Stay patient, work hard and be dedicated. Results will come.
Everyone is different. You will learn about your body on the go and you can tweek your diet and workout to what works for you. No one method fits all.
Rest or/and diet is as important as the workout. Workout triggers the growth, true. But you grow when you rest and the fuel comes from the diet. These are equally (if not more) important.
Form, Form and Form. Doing 2 counts of any exercise properly is better than doing a 100 otherwise.