If you want your website to actually appear under the domain name you purchased, which I trust you do, you will have to use Website Maker to build and publish the website. Make sure to tick the new domain name in the dialog you get after clicking the "Publish" command.
There is a possibility to connect to the Magix online services account via FTP and upload e.g. an HTML-based site. However, at the moment there is no way you can make this content show up under the domain name, so this isn't really relevant to your use case. If you're still interested in this option, have a look here: