I have now done a bunch of 'How to - -' do things documents about starting to use Joomla! They are not finished because they are never finished. They are in the same format as Wikipedia - so I can go on editing them for ever. Unlike a book - they don't get copy-edited but they do get seen rather sooner.
I have spent a lot of time editing and writing these - which is one reason I have not written as many blogs as I would have liked. They are due to be released into the wild - that is to say - linked from the main Joomla! site - maybe the end of the week. This is the importance because thousands of people use the site.
Joomla! is free at the point of download. It is a Content Management System - used for - um - managing the content and layout of lots of web sites world-wide. Some small business, clubs, associations use it - as do bigger outfits. More on this and the ecosystem that is Joomla! in another post.