How to Bulk
In order to put on weight you need to eat more calories than you expend. However, excess calories can turn into fat if you are not exercising. The key is to find a medium where you are fueling your muscles so they can heal and grow between workouts, while burning any consumed fat through some kind of cardio.
During a bulk, many people focus on meeting certain calorie intakes each day. I tried this for about two weeks and found that I was force feeding a lot by dinner time. My appetite has never been very big, so force feeding felt like torture. Although I was not bulking conventionally, I managed to put on weight by eating high protein, low fat foods (i.e. chicken, peas, peanut butter, cliff bars as snacks, protein drinks, etc.) while lifting and running.
From August to December, I lifted every morning, and played basketball or lacrosse about 3 to four times a week. My workouts allowed me to continue gaining muscle mass and strength, and basketball and lacrosse served as cardio that allowed me to burn any consumed fat. In my workouts, I emphasized drop sets on bench and other iso exercises. Drop sets are progressive sets of an exercise where you start heavier, and progressively lift with lighter weights each set until failure. This promotes muscle growth and stamina. As long as I was eating enough protein and nutrients, and drinking enough water to help my muscles and body recover, I was continuing to gain lean muscular weight.
You want to make sure you are bulking by consuming clean calories. Do this by eating a little bit more after you are full. If you have room for dessert, eat something healthy instead. After meals I would have a protein drink/bar, or make a peanut butter and jelly sandwich, or even just have one more chicken breast. You could also drink soy milk, or have some peas. It is up to you and your preferences–whatever you can easily eat. This will help you consume more calories and protein at the end of each meal.
Lifting, fun cardio, high protein foods that are clean, and some extra protein-filled food at the end of each meal in combination will help you put on lean muscle mass. This is how I went from 160lb to 190lb at 6’5” in five months.