First of all add a reference to your WCF service in your website like this
How to: Add a Reference to a Web Service[
^]
this will generate proxy code with the name you've chosen so say you'd chosen to call your reference 'Acme' and it support a method called 'RegisterReferrer' with one string parameter, you can then use it like tis
using(var proxy = new Acme()){
proxy.RegisterReferrer(Request.ServerVariables["HTTP_REFERER"]);
}
Of cause you don't need the Request.ServerVariables["HTTP_REFERER"] bit i was just putting anyting in the string variable for the sake of the example