It is quite easy just go to the Account and settings in that account, Click on add new device Apart from this If you have another issue you can call amazon support Kindle Technical Support Registration 877 690 9305
You should be able to register with your account simply by logging in to the kindle app or kindle store with your amazon credentials on your new device. I don't recall if that is how it works with the paperwhite versions, but on the android based systems (even non-kindle devices) the device shows up on the amazon device management section of my amazon account on the website when I log in with my amazon credentials.
Answers & Comments
It is quite easy just go to the Account and settings in that account, Click on add new device Apart from this If you have another issue you can call amazon support Kindle Technical Support Registration 877 690 9305
You should be able to register with your account simply by logging in to the kindle app or kindle store with your amazon credentials on your new device. I don't recall if that is how it works with the paperwhite versions, but on the android based systems (even non-kindle devices) the device shows up on the amazon device management section of my amazon account on the website when I log in with my amazon credentials.
Good luck.