Just in case you are interested in testing a site in your local programming desktop computer...
Then you'll need a set of programs that will allow you to use JOOMLA in your computer.
Your server will have it installed and in order to be able to use it in your computer you'll have to do the same.
Get
EasyPHP[
^],
WAMP[
^],
XAMPP[
^] or any of those suites and donwload the JOOMLA extensions, then configure them (typically following samples from the web) and that's all...
Good luck!