Question

if apersons cloth catch fire what we have to do

Answer 1

take a blanket and wrap it around the victim n make him roll at the ground or use  fire extinguisher if available

Answer 2

if a person's cloth catches fire we should the 1st thing we should think is that how to stop the supply one any 1 thing which helps to lead fire burn therefore according to me the best way is to cover him with a blanket /any other cloth so that oxygen can't be supply and thus fire will automatically cool down.
               i hope that this will help u.....................^_^