You have to follow this steps:

1. Log in as a user in Unlugar.com

2. When you enter to your Control Panel, click where it says ¨Register or transfer a new domain¨

3. In the next screen fill in the data and where it says ¨Plan¨ choose the one you have hired.

4. And ready. You can upload the files through FTP and in 24 hours you will see your site online.