XML comments are implemented in XComment class.
You can create a comment and add it to its element on the fly using functional construction.
using System; using System.Linq; using System.Xml.Linq; using System.Collections.Generic; class Program// w w w. j a v a 2 s. c o m { static void Main(string[] args){ XElement xBook = new XElement("Book", new XComment("This person is retired.")); Console.WriteLine(xBook); } }