SOAP missing HEADER

Here is the way I call the web service in .net 3.5 and bind with Cert:
webservice.getData webData = new webservic.getData();
webData.myObject webObj = new webData.myObject();
webObj.myID = "ABC";
webObj.myName = "John";
X509Certificate cert = X509Certificate.CreateFromCertFile(@"C:\mycert\mycert.cer");
webData.ClientCertificates.Add(webObj);
strReturnData = webData.myRequest(myObject).ToString();
I want the output like this:

...

...



Problem:
I could not generate the HEADER in the SOAP.  Any solution?