hariyatama kiyanda danne ne. but first they have a training period before becoming a nun. they are not wearing the nun robe but wear something white and put a head scarf too when inside the church. once the training period is over the bishop blesses them and give them the nun status. even there are some stages in a life style of a nun. from the start to and to becoming the head nun. most sisters don't come to be the head nun. Well to get more info u have to ask from a nun machan or a daham pasala teacher.