First, create a file and call it info.php and call phpinfo in it ( <?php phpinfo() ?> ) and then create such an url :
http://www.you.com/info.php/a/app/c/caa
Note the information within your REQUEST_URI variable, see it? You're going to be using it and the explode() function, try :
$values = explode('/',$REQUEST_URI);
And see what kind of information the array $values provides. That's the most basic way of doing it. Also, see :
http://phpbuilder.com/columns/tim19990117.php3
