Please, please, please do not ever mention w-3-s-c-h-o-o-l-s dot com again. That site is GARBAGE and usually totally wrong. It results in more bad code than nearly any site on the internet.
WSDL is a language to describe an API interface. You should be able to use the contents of that file to create an object to help you call the functions defined in the WSDL file. WSDL is a way to expose a server's functions to the world so that external clients can call server functions. You might find some helpful sample code here:
http://us2.php.net/manual/en/soapclient.soapcall.php
My experience with WSDL is that not every SOAP client interprets the WSDL code the same way and this often leads to errors or other problems. For example, an ASP.NET script might use some windows library to parse the WSDL code just fine and operates well, but the PHP SOAP parser won't work. Other problems are that the publishers of web services often don't document which parameters are required or what value types to use or what parameter values are acceptable. It's usually helpful to know the guy who maintains the WSDL gateway so he can tell you what went wrong with your request.
