Hey there, I’m not sure we have any other members trying to gain weight, we’re all the opposite.
My husband however is a naturally lean person who has struggled to gain weight but had success more recently, it depends on your lifestyle.
He has 4 meals/day, including a large one at lunch time. He doesn’t eat much rubbish at all and concentrates on a good chunk of protein (a lot like BSD) healthy additions, plus complex carbs. He is free-er with his carb intake than most of us here. He also does some strength training and I’m certain most of his gain is muscle rather than body fat.
I’d definitely not turn to the rubbish carbs as you may gain a healthy weight but will end up unhealthy in all the other ways. Eat more food of the healthy variety is all I can really suggest.