Go to the Club Penguin homepage and there should be a coin with the words 'Unlock Items Online' around it. Click on that and it will ask your penguin to sign in as usual. But instead of going to the server page, it will take you to a page which asks you what you have got to unlock. Click on the option which says 'I have a code' and it will take you to a page which has a bar on it. Type your code in there and press 'Enter'. It will then take you to a page which will show you what you have unlocked. It will then give you the option to whether you want to unlock more codes, or go onto Club Penguin. Choose what you want to do. If you choose to enter another code, it will send you through the process again. If you choose to go to Club Penguin, it will send you to the server page. Hope this was helpful!