43 years old need help gaining weight and muscle mass

tankmonk1973

My names Richard. I'm 43 years old. I need help gaining weight and muscle mass. I paint water tanks for a living. I climb anywhere between 120 to 160 feet up in the air at least four times a day. I am constantly moving whether in the air or on the ground. Usually do not take lunch. My eating habits are poor. Some days i barely eat a bite others i cant get enough. When i do eat its mostly junkfood. Please help need all the advice i can get. Thank you.