By mistake I have selected Mr instead of Ms in the name of person. So how to change it? I have e-ticket of it booked on IRCTE.
The general answer to this is phone the booking company (or airline directly) and be prepared to pay an admin charge. Do not leave this to the last minute as you often can't change within a window before the flight (and having tried to do this in the airport before I know that doesn't always work ...). Note that sometimes it isn't possible at all.
The specific answer can be found on IRCTC FAQ here: http://air.irctc.co.in/flights_faqs.html
Now, I think they mean you can't change the name directly with the airline, but can with the booking service (although I suspect most airlines will change the name, but maybe only the booking service can prove that you are who booked the ticket).
This is the Customer Support number (from the same page):
I'd be interested to know how you get on, since that FAQ answer is a bit contradictory.