Login to your Amazon Associates account (https://affiliate-program.amazon.com/home).
On the top right, beside your username you will see your ID.
Click on the edit button
and put your amazon id on the LinkDeli input box, including the dash and the 20 at the end.
You only need to do this process once.
Tip: After you have set your affiliate links, you can check, if they are correct by previewing the full affiliate link.
While in the edit mode of the list, click on the preview icon
and the full affiliate link will be displayed to check it.