You must have a webservice like this http://localhost/MyWebService.asmx
For retreive your webservice wsdl you must put this address at the browser address bar:
If you want to use this wsdl, you must go to the visual studio and add web reference with the wsdl address. You can also, generate your service proxy by command-line, executing:
Check your configuration file for this setting:
The httpGetEnabled attribute must be set to true.
I suppose you are using WCF