More than one service?

Hi all:
suppose I've got a rather large webservice that could easily be subdivided
into two service groups: Administration webmethods and User webmethods. So I
have put two System.Web.Services.WebService objects into the project. But:
how can I assign a special port to call one of the services, see the correct
wsdl and call the specific method from a client?

Thanks for advice
BP