Before you can understand how to operate Joomla!, allow me to explain the basic principles that underlie the system.
Content Management System
Content Management System (CMS) contains the terms content and management (administration), that imprecisely refer to a system that administers content. Such a system could be a board and a piece of chalk (menu or school chalkboard), or it could be something like Wikipedia (the free online encyclopedia at http://www.wikipedia.org), or an online auction house such as eBay (http://www.ebay.com/). In all three of these cases contents are administered, in the last instance by numerous participants. These participants play a major role with content management systems: on the one hand as administrators and on the other hand as users.