Hello this is mahesh I have a problem with my physique. I look thin my age was 20 and my height was 5feet 11inches but my body weight is 56.so can u please inform me how to gain body that look good for my height and age .

Some people are just naturally thin,if you have no medical conditions and in good health,pilates is a good way to tone and build muscle,also resistents training using weights..
Ask at a gym for an exercise routine that would best suit your needs.