What's the best method to gain weight?

Below: If you consume more calories than you expend during the day, you will gain wt. Any online calorie counting site will give you information about the calories in food.

Weight gain: weight training and high protein diets.

Eat, eat, eat.: You can gain calories by just eating more food. People tend to gain weight with meat because it's more calorie-dense than other foods, but you'd gain more weight by just eating more of less calorie-dense foods. Just keep it healthy - there's a difference between gaining muscle weight and just getting fat. And exercise as well, so you gain lean mass and not just get fat.