For this you have to install the app from your play store.
Register it with your email id and mobile number.
Now you can see 2 credits on my screen.
Now claim the two credits, it will be added in your account.
Now add these credits into your amazon cart as a gift card.
By clicking add to cart, the two credits will be added to your account.
Now when you will be having total 10 credits you can redeem them, in simple these 10 credits are equal to 200 rupees.
In some devices this app version is not compatible. So you can directly go to the website and download the app from there, by registering it on website using your email id.