There are three key concepts to understand when getting started with Joomla: 1. Administration involves a public-facing front-end and a private back-end for site management. The front-end is at www.abc.com and the back-end is at www.abc.com/administrator. 2. Content refers to articles published on the site. The Content Manager is used to edit articles on the back-end that are then published to the front-end. 3. Navigation involves menus to help users navigate the site. The Menu Manager controls how menus work and the different types of menu items that can be created, including single content items, multiple content items, URLs, and RSS feeds.