What to do if i want to gain weight the healthy way. what kind of food should i eat?

Complex carbohydrate: 5-7 servings of fruits and vegetables a day. 3-5 ounces of lean meat, chicken or fish as protein, or eggs, or 1 cup of milk. Complex carbohydrates as whole grains, 1/4 of your plate servings. 1/2 your plate should be fresh fruits and or vegetables. And 1/4 of your plate should be protein. Beans and legumes are also healthy carbohydrates. Take in more calories than you need and you will gain.