You need a PHP capable server (most have Apache installed) with an SQL database. Installation is simple, download the
package from their website and then upload to your server and extract it. You can set the rest up from your browser, there's no need to manually mess with any config files. Just go to the directory where you installed it and fill in all the fields.
Requirements
-Web server such as Apache or IIS
-Local or command line access is needed for running maintenance scripts
-PHP version 5.0 or later (5.1.x recommended, for api.php to work)
with Perl Compatible Regular Expressions
with Standard PHP Library
-Database Server
-MySQL 4.0 or later
or PostgreSQL 8.1 or later
-Requires PL/pgSQL (contained in contribs)
-Full-Text searching (Native in >=8.3, requires tsearch2 extension <=8.2)
Installation guide