<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<header>

+<TAG1>*
    $<TAG2>**
    </TAG2>**
    +<TAG3>**
        $<TAG4>***
        </TAG4>***
        +<TAG5>***
            $<TAG6>****
            </TAG6>****
            $<TAG7>****
            </TAG7>****
        </TAG5>
        $<TAG8>
        </TAG8>
   </TAG3>**
</TAG1>

</header>

File outputFile = new File("C:\Users\User\Documents\test.xml");
DocumentBuilderFacotry dBFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder dB = dBFactory.newDocumentBuilder();
org.w3c.dom.Document doc = dB.parse(outputFile);

org.w3c.dom.Element tagTest = doc.createEleement("tagTest");
org.w3c.dom.Element node = doc.createElement("newNode");
org.w3c.dom.Text text = doc.createTestNode("data");
node.appendChild(text);
tagTest.appendChild(node);


TransformerFactory tFactory = TransformerFactory.newInstance();
Transformer transformer = tFactory.newTransformer();
transformer.setOutputProperty(OutputKeys.ENCODING, "UTF-8");
transformer/setOutputProperty(OutputKeys.INDENT, "yes");
Writer out = new StringWriter();
transformer.transform(new DOMSource(doc), new StreamResult(outputFile));
System.out.println(out.toString());