creating an xml message

Quick question:

I am trying to create a new xml message with the following at the top:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE myMessage SYSTEM "myDTD.dtd">


This should be pretty simple, but this is all I have so far:

DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        try {
            DocumentBuilder builder = factory.newDocumentBuilder();
  
            document = builder.newDocument();

....



I believe the second line is a DocumentType Node, but how is the first line
created?

Thanks,

Miguel