Eat and eat and eat and don't do much and sleep.You are a ectomorph which means u can eat a lot of food and u won't get fat at all. but if ur trying to gain weight as fast as possible eat very fatty foods throughout the day and have like a five hour period before u eat again, but this is very unhealthy, so just intake one gram of protein for every pound u weigh everyday.Focus on what you like about yourself. Stay positive! If you want to weigh more, you still want to be healthy. Eat fresh food, like homegrown veggies, fruits, and meats. If you're really concerned, ask your doctor the next time you visit him/her.