Gaining

Exercise a bit, like mild weight training and try to take a walk a few times a week.

Avoid saturated and trans fats. Go easy on sugar.

Lots of bread, pasta and other foods high in carbs.

That's my two cents. However I am not a food expert, just trying to use common sense.

The bad fat is in the muscle, the belly (men hurts more to be fat than women), the good fat is the butt and legs, which is above the muscles, it is softer (and sexy).
I'm not a doctor, so I do not know, but you should eat much in the evening and a little in the morning, better not to overdo things with salt and too much sweet. (I like to eat pasta, you should eat so much with so many sauces).
To many people, the belly grows before that the legs, if so try to do some abdominal exercise, do not overdo it