ТЕМА:

private string Serialize(Object o)
{
    using (var writer = new StringWriter())
    {
        new XmlSerializer(o.GetType()).Serialize(writer, o);
        return writer.ToString();
    }
}

using System;

public class clsPerson
{
  public  string FirstName;
  public  string MI;
  public  string LastName;
}

class class1
{ 
   static void Main(string[] args)
   {
      clsPerson p=new clsPerson();
      p.FirstName = "Jeff";
      p.MI = "A";
      p.LastName = "Price";
      System.Xml.Serialization.XmlSerializer x = new System.Xml.Serialization.XmlSerializer(p.GetType());
      x.Serialize(Console.Out, p);
      Console.WriteLine();
      Console.ReadLine();
   }
}

public void Save(string filename)
    {
        var ser = new XmlSerializer(this.GetType());
        using (var stream = new FileStream(filename, FileMode.Create))
            ser.Serialize(stream, this);
    }