How to write my sur name and last name?

Question

My name : gangadharan

Father's Name : Kasi rajan

Answer 1

What is your full name (as given on your birth certificate) and what do you need this for?

Some people, for example from some places in South India, do not have surnames or a last name.  Instead you might use the name of your village or a single letter initial of the village name or their father's name.