Spammers will be blocked and bombed.
What is Joomla!
Joomla is an Open Source Content Management System. It is a php/mysql application which means that it is written in php and uses a MySQL database, usually administered using phpMyAdmin, a GUI for administering the website databases.
My Joomla notes are here on my Tiddlywiki.
How to install Joomla
You will need an Apache based website host provider which hosts PHP5 and MySQL based programs (most do). What that means is that you can upload any program that uses php into a designated online folder and it will most likely work. Take a look at what Siteground offers for a better idea. It's quite a complicated business so you will need some time to learn how to do it yourself. Luckily most host providers will install everything for you via an automated script that you can request, just to get you started.
How to install Joomla offline
You can create a mirror image of what your commercial website host provider is using on your own PC by installing a suite of programs that includes all you need to turn your PC into a virtual Web Server, accessing your site and adminitration options via your browser from an http://locahost address. My offline (on my PC) Joomla installation which I use for testing is http://localhost:85/joomla. /joomla represents the folder containing my Joomla files.