Joomla is a rather powerful, yet easy to use CMS. To see how it works, follow this link.
You can also log in to the back-end from here and enter the following information to log in:

Username: guest
Password: guest

Content Management System (CMS)

A CMS is a program that is used the manage the content of a website. It stores user-created articles in a database and allows the user to manage their publishing, access rights, etc. Most CMS's allow the web site to be displayed according to a theme which defines the look and feel of the website. Examples of well-known sites based on a CMS are wikipedia.org and washingtonpost.com.