Good nutrition is a vital part of any training regime, especially if you're aiming to increase muscle mass. You need to make sure you have plenty of quality protein in your diet, as well as extra calories to support the anabolic processes that build muscle.
You might need as much as an extra 500-700 calories per day if you're aiming to increase muscle mass. This should be in the form of complex carbohydrates to avoid swings in blood sugar levels. Regular small meals are best and weight gain powders can help you achieve your training goals and add good quality muscle mass by supplying the body with complex carbohydrates and quality protein all-in-one formula.