When you add an item, you have the option to directly enter the URL of the item you wish to add. To do this, visit the webpage of the item you want, select the URL and right click. Select "copy". Return to the Christmas List App add item page and paste your link. To do this, right click and select "paste".
Check out our Google Chrome extension to eliminate this process. You can install this (for free) and then directly add items to your list right from the website that has your item.