Go to Tamatown.com and type in your username and look around for the king's castle (By the mall) and then simply click on it and type in your password and yo will recieve your prize!
Whenever you get a password be sure to write it down or leave it on your Tamagotchi so you can always get back to it. Because as far as it goes for the Tamagotchi king passowrds.....yo can not get them back and only can by reseting it. So be sure to write it down or leave it on your Tama.