Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question.
The process is simple enough.
1. log into your Amazon.com account (the one that your Kindle is registered to.)
2. go to
and transact the payment, by means necessary or available or convenient (a credit card perhaps? if so, it has to be one that is registered as a means of payment for your Amazon.com account... and if you need instructions on how to do that, how to register a credit card into your Amazon.com account, please let me know and I will guide you through the process.)
(If this answers your question fully, please rate my answer. Five stars would be fine! but if you need more instruction, that can wait. Thanks.)