First of all, if you want to build a muscle, you must first increase your own meat. Many thin people want to exercise muscles instead of eating meat. The muscles that are trained are not beautiful and practical. Eat meat first and then practice muscles. Such people usually eat very little at every meal. You can eat less and eat more at this time. Just eat less and more at every meal.
The second way is to eat something high in protein. Everyone at school should know that those sports students will eat some protein powder when they exercise their muscles. Because muscles are made up of various protein, it is said that supplementing this stuff can make them gain weight and muscle. However, a certain amount should be set every day. Eating too much will be counterproductive.
So if you want to gain weight, exercise your muscles. You can try these two methods.