PayPal does not have a feature of transferring money from card to PayPal balance. However, if your prepaid card has a routing and account number, you can add these details to your PayPal account and use it to add money to your PayPal balance.
You don't need to add money to your PayPal balance for you to make payments, though. You can just keep it at zero and choose your prepaid card as funding source when you make a payment.
