Hi, I'm 28 Now And Am Very Skinny, I Want

Hi, I'm 28 now and am very skinny, I want to gain weight according to my age. I drink thrice a week and smoke daily. I also masturbate once every night and the foods I take is very little cuz I can't take it much my stomach becomes full. So pls suggest me what should I do and what I should not and also tell me which weight gainer supplement will help me.