The best way to do this is through the Getting Started training - Just as Labman mentioned. If you want to go directly to creating a free website you can click on the light blue SiteRubrix button in the upper left hand corner of the page. Then click on the site builder and you should see an option to create a free website. Again it is best to follow the training!

The training will teach you how to do this. Click on the green button that says get started here. That will walk you through how to build your site.