I have a coldfusion webservice that returns an XML file. I want to secure it so that the user needs to authenticate inorder to consume the service. I have to be able to pass the users credentials to the webservice via VB6. I haven't done anything with webservices or SOAP until now and i am unsure how to structure it. I have also heard about REST but i am not sure what the differences are. Can anyone help? Below is what i think it should look like but i am not sure. Any help is appreciated!

Code:
<?xml version="1.0" encoding="iso-8859-1"?>
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
<soap:Header>
  <AUTHENTICATION>
    <USERID>STRING1</USERID>
        <PASSWORD>STRING2</PASSWORD>
   </AUTHENTICATION>
  <PARAMETERLIST>
    <IDNUMBER></IDNUMBER>
   </PARAMETERLIST>
</soap:Header>
<soap:Body>
 <TEST1>
    <TEST>
      <NAME>string</NAME>
    </TEST>
 </TEST1>
</soap:Body>
</soap:Envelope>