Joomla! is a web content management system (WCMS),
CMS is more commonly used than WCMS.
however if you ever happen to have any problem using our software, you can seek out for help at the Joomla! website or at the Joomla! forums.
You make it sound like there is no one to help you. Make sure you don't give anyone this impression.
content management system (a tool for creating highly productive web sites)
You just mentioned what a CMS is before.
Joomla! is 100% FREE.
Joomla! is very secure.
Joomla! is very easy to use.
Joomla! is very robust and reliable.
Joomla! is elegant, flexible, customizable, simple, powerful.
You did not even mention that Joomla! is free (as in freedom) and open source software! This is the biggest advantage to using it!
Joomla! is a pretty powerful application, however it's true power comes from Joomla!
Extensions. Extensions are add-ons or PlugIns that can really make Joomla! powerful.
Extensions!=Plugins. Plugins are the replacements for Mambots.
Joomla! has many advantages over competition: the number one is Joomla! Extensions (see Joomla! Extensions section).
You've talked about the extensions, Move on to bigger and better things here.
Joomla! has a very powerful and easy to use administration (with a graphical user interface of course!).
This sentence doesn't make sense.
Creating a Web site can significantly increase your business' productivity, because customers will be able to find out what your Business is all about without having to talk to you in person or over the phone, because many people are simply shy, or do not want to walk down the street (or [drive] to the other side of town), this way, all information about your businesses is but a click a way.
This is a run on sentence. Split it into 3 or 4 new sentences.
It would also be a good idea to add a caption to your images.