XML : Android internal storage xml child nodes

I have created internal storage xml file and added parent nodes to it by

  String data="<?xml version='1.0'?>\n<parent>\n</parent>";  fos = openFileOutput(fileName + ".xml", Context.MODE_PRIVATE);  fos.write(data.getBytes());     

Now i want to add child nodes between parent nodes. After user has filled text field (example "Romeo") and pressed the button. New entry will be added after last one.

  <?xml version='1.0'?>  <parent>    <child>      <name>Jon</name>    </child>    <child>      <name>Romeo</name>    </child>  </parent>    

I know how to do it in pure java but i have no idea how to do it in android.