Where to add payment details here?

Let me clarify it. You don't have to request for your

 Payment if your payment profile is already completed. 

In the Dashboard section, click on pay profile and updated the details there. 

Thanks a lot. I will check. What is the payment method of the site? Is it through PayPal or bank transfer ?

This site pays via direct bank transfer. You can check the amount you earned on your dashboard. Once you reach the minimum amount of Rs1500, you cann send a mail requesting for payment with your ban details. This is for first time payment. After that your payment will be processed as soon as you reach the minimum payout from next time.