Skins are the variations of the presentation layer (or “theme” in Drupal lingo) that provides the look and feel of your site.
A key reason for using a content management system such as Drupal is to spread out the work of adding content to your site. Roles and user accounts make that possible.
Your Drutopia site comes with a home page that will pull in elements from various content types as well as custom blocks that you can customize.