I m thin.. skinny.. some one told me to have beer..will that be usefull?

Empty calories.: I think they may have been teasing you. If you are skinny, you can afford to take in the extra carbohydrates and extra calories, but it will do nothing positive for you if you are trying to gain strength and muscle. Eat a healthy diet with protein, fruits, vegetables, whole grains, and healthy fats( the kind found in olive oil and nuts), and make sure you exercise regularly. Good luck to you!