Details on how to get your name added in the electoral roll http://india.gov.in/howdo/howdoi.php
Know your MP/MLA of your constituency on this website. I am trying to see how i can contribute - i suggest we all do that. But there is not too much information on this site. Just a listing of MP's that i could find. MLA's are impossible to find. I have also never heard of most of the constituency names in the list. Still, worth checking out.
http://www.mpmla.in/index.php

http://www.eci.gov.in/

I suggest you put this in your favourites list and check it as often as possible. This is the government's election commission website. It has details on where to go and register yourself in an electoral roll. Check the state election commissioner's website for the address.
So the tie-in on these sites are:
Through MPmla.com, find out who is elected. Then go through the guidelines on voting. Find out about your state election commission HQ and get yourself on the electoral roll.