title_body: how to redeem Amazon gift cards on a Kindle?
upvoted_answer: I'm guessing that the reason you are asking the question is that for some reason you don't have access to the account associated with the device. YOu could probably check with the Amazon people, but I'm pretty sure that the only way to redeem a gift card is via a web browser and only if you have the account holder's login/pass. 
  
  Another option is to just wipe it clean and create your own account. 
  
  If you have ebooks that you want to add to the device and they are not encrypted with DRM, you can add them via usb.