jquery ajax call custom web service asmx

Question

Hi, i need to access custom web service based on Sharepoint 2007 with jQuery. This web service has some operations (oper_get_smt1(), oper_get_smt2() ... )

I should probably use .ajax() function. But i don't know how to correctly define URL parameter.

$.ajax({
                type: "POST",
                url: "http://site/_vti_bin/webservice2.asmx/returnCustomBanking",
                data: "{}",
                contentType: "application/json; charset=utf-8",
                dataType: "json",
                success: function(msg) {

                  $('#data').html(msg);
                }
              });

Please for any advice .. what to do.