Page nodes are hierarchical content organised in menus. Out of the box, your Sector site will have two public facing menus - the main menu and a tertiary menu (footer).
From May 2020, the new media library replaces the Sector media browser for images, files and videos with one robust, easy to use, and customisable interface.
Once you've logged in to your user account, you'll see the Administration User Interface (AdminUI). This has two distinct areas: the AdminUI overlay on the frontend of your site, and the AdminUI backend.