how to add comment in xml

using System;

using System.Linq;

using System.Xml.Linq;

class Test

{

   static void Main()

   {

      XElement TestSet = XElement.Load("pramod.xml");

      XElement[] elements = TestSet.Elements("Test-Case").Where(e => (int)e.Attribute("TSID") > 144514).ToArray();  // get the last two elements

      string content = elements[0].ToString() + "\r\n" + elements[1].ToString();

      XComment comment = new XComment(content);

      elements[0].Remove();

      elements[1].ReplaceWith(comment);

      TestSet.Save("pramod2.xml"); // save to different file while testing   

   }

}