One of the most hyped up and over embellished areas there is. People talk complete and utter garbage about weight gain.
I will tell you how I bulked up from a 14 st 3 lbs amateur heavyweight boxer to a 18 st Superheavyweight.
I did it over a summer, back in 1995. I used the following exercises and ate as a 17 st man should require, with increased food cals intake and protein supplementation, also with Creatine/ Glutamin mix ( Sponsored by Star Max)
3 sets of 10 reps on each to failure.
1. Leg Press/ Squat ( I am 6ft 5 with a bad back, so leg press much better for me)
3. Chins or Pull downs (Chins better)
4. Seated rows
5. Bench Press
6. Shoulder press
7. Upright rows
8. Shoulder flies
9. Bicep curls
I used to take a pre workout drink with Creatine and attack this session
I would do it 3 days a week and the off time along my muscles to grow.
If you want to maintain fitness, utilise my cardio workouts on alternate days.