How to add new element inside XML file using ASP.NET VB

Private Sub newnode()
    Dim file As String = Server.MapPath("note.xml")
    Dim xmlDoc As XmlDocument = New XmlDocument()
    xmlDoc.Load(file)

    Dim newXMLNode As XmlNode = xmlDoc.SelectSingleNode("/Courses")
    Dim childNode As XmlNode = xmlDoc.CreateNode(XmlNodeType.Element, "Course", "Course")

    Dim newAttribute As XmlAttribute = xmlDoc.CreateAttribute("name", "sree", "asd")
    childNode.Attributes.Append(newAttribute)
    newXMLNode.AppendChild(childNode)

End Sub