You have to eat alot to gain weight, and I would not reccomend taking any supplent.
You best way to gain weight is eating heathy
eat aleast 5 to 6 time a day in divided into six small meal. Eat healthy, breakfast eat oakmeal with banana, cup of orange juice two egg white only, yoke is bad, to much cholestrol, two slice bread with strawberry jam.
between breakfast and lunch, eat two banana, some grape or an apple, peanut butter sandwhich.
lunch,, I would eat, a 6 0z tuna, broil, fry or skiness chicken breast with 2 cup rice. one to two cup water.
before dinner I eat some an apple, 1 banana, some grape, some vegeble, broccoli, salad. and for desert drink a milkshake, or cheese cake.
Dinner eat some spagetti, with meat ball, or chicken with some bread and some vegeable like broccoli or corn.
that just an example of what I eat, so be creative, and eat healthy. Have a well balance diet and drink a lot water to.
I would also reccomend join the local gym and workout over there too.