Specially for yyassaman :)
The Joomla! Web Content Management System (CMS) allows the content manager or author, who may not know HTML or any other programming language, to manage the creation, modification, and removal of content from their Website without needing the expertise of a Webmaster. The most important thing you need to know is that having a CMS is about using the web with purpose – for your business and your bottom line.
The software behind the CMS takes the content that is entered and compiles it so that the Website is instantly updated. The features of Web CMS’s vary, but most include Web-based publishing, format management, revision control, and indexing, search, and retrieval functions.
The Joomla! CMS has a wide range of features and layout options, and works with a huge range of modules and components to give you and your users extra functionality.
I searched the Net for some stuff but all that I could find was this little book. It's quite helpful though, especially for someone new to the technology.
BTW, it is FlashPaper format (.SWF) you may view it in Internet Explorer.
You may also check the following post by douchon also:
Please visit http://www.joomla.org to download the software.