Unfortunately, you can't register your product anymore because it is an old one that is no longer supported. If you want, you can upgrade it to the latest version. In this way, you will receive a password that will help you to activate the product. Navigate to the official web page, click the first yellow Upgrade now button, select Photoshop Elements 4 from the I own drop down list and follow the on-screen instructions. The upgrading price will be around 79.99 dollars.