The "Subpage Default" is your default sub page and displays the page content at full width of the page container.  The "Subpage Sidebar" will display the content with a right sidebar.  The "Style Guide" page has been setup to display your site default styles.

The page will automatically display the page title at the top of the content area.  The checkbox "Hide Page Title" removes the title from the page.  The page description field is optional.