i want to modify xml element using stax in java

XMLOutputFactory xof = XMLOutputFactory.newInstance();
XMLStreamWriter xtw = null;
xtw = xof.createXMLStreamWriter(new FileWriter("eman.xml"));

XMLInputFactory factory = XMLInputFactory.newInstance();
      XMLStreamReader xmlReader= factory.createXMLStreamReader(new FileReader(fileName));
        int eventType;
       while(xmlReader.hasNext()){
              eventType=  xmlReader.next();
              if(eventType==XMLEvent.START_ELEMENT)
              {
                  QName qNqme = xmlReader.getName();
               if("YURTAG".equals(qNqme.toString()))
                {
                DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
                DocumentBuilder builder = factory.newDocumentBuilder();
                File file = new File("YOURXML.xml");
                Document doc = builder.parse(file);
                //make the required processing for your file.

           }

       }