First register your Number in payback, which can be done going through their official website. ( If it is not done at time of taking the card).
Download Mobikwik and use this Same number and Email as of Payback. ( To make sure things go pretty smooth).
Connect your Payback account with Mobikwick using option provided in Mobikwik settings.
Authorize your payback account and it will show the number of points and here 4 points =1 Rs.
Then enjoy your drive. Hope this helps you