How to register the licence of an iLife '08 DVD in order to be able to update iWeb 2.0.3 to iWeb 3.0.4?

How to register the licence of an iLife '08 DVD in order to be able to update iWeb 2.0.3 to iWeb 3.0.4?

I purchased a retail license for iLife '08 and now I have installed iWeb 2.0.3.

I am unable to upgrade it to iWeb 3.0.4 because an error message comes up that says:

"iWeb Update can't be installed on this disk. A qualifying copy of iWeb was not found in /Applications."

How can I do to REGISTER on Apple's site the copy (license) of the DVD I purchased and successfully upgrade to version 3.0.4?

The device is an Mac Pro 3,1

The topics is related to the upgrade of iWeb

Thanks so much for your welcome and kind replay to my question.

The operating system is "El Capitan" 10.11.6

The installed copy of iWeb 2.0.3 works just fine.