VB.NET: Append string to Xml file

[toytoy]

Hi

Say i receive one string full of Xml tags ...

Example: "<Person>John</Person><Item>Pen</Item><Amount>4</Amount>"


How to save and append these tags to my xml files..

They told me to use appendChild method.. maybe i am not quite sure with string....... i save the string two times instead..
I am using VB.NET....

 Dim myDoc As New Xml.XmlDocument
 Dim myXml As String
  myXml = "<Person>John</Person><Item>Pen</Item> _  
 <Amount>4</Amount>

  myDoc.LoadXml(myXml)

  Dim root As XmlNode = myDoc.DocumentElement

  Dim person As XmlElement = myDoc.CreateElement("Person")
  person.InnerText = John

  Dim itemy As XmlElement = myDoc.CreateElement("Item")
  item.InnerText = pen

  Dim amount As XmlElement = myDoc.CreateElement("Amount")
  amount.InnerText = 4

  root.AppendChild(person)
  root.AppendChild(item) 
  root.AppendChild(amount)
  myDoc.Save("1.xml")

How to solve this so that it will append to the xml whenever i receive a string...

Thanks.