When you are logged in to your iwantmyname account, please send us a support ticket asking us to add the Zenfolio records to your domain:
We will advise once this has been completed. The new records will take a few hours to propagate, then you can complete setup in Zenfolio. To do that, go to Step 6 Test your DNS here: https://www.zenfolio.com/u/e/settings/website/updatedns.aspx
You may see things start working within a few minutes, but please remember that it can take up to 48 hours for DNS changes to fully propagate around the internet. So your website may not show up in all browsers immediately.