If you want to use your registered domain in the sitebuilder the first thing you need to is to point it in your control panel. Start by logging into your control panel so that you arrive here:
Click the sitebuilder icon so that you continue to this page:
It is here you choose to point your domain to the sitebuilder so that it becomes the primary domain, what you need to do is to select your domain in the list where it says Map Domain as you can see here we have chosen the test.mhdemo.se:
When you press the "Map" button your domain will be added to the list as you can see here below:
Usually the domain is automatically set as the primary one but if not, then you just need to click on "Make primary" and your website will be published to your domain.