C# Read and write XML (code sharing)

XmlDocument xd = new XmlDocument(); 
      string fileName = @"D:\";
      (fileName);
      XmlNodeList xmlNoteList = ("user");
      List<User> users = new List<User>();
     
      foreach (XmlElement item in xmlNoteList)
      {
        User user = new User();
         = (("id"));
        XmlNodeList xnl = ;
         = xnl[0].InnerXml;
         =(xnl[1].InnerXml);
         = xnl[2].InnerXml;
        (user);
      }
      foreach (var item in users)
      {
        (item);
      }

Read XML

<?xml version="1.0" encoding="gb2312"?>
<users>
  <user id='1'>
    <name >Zhang San</name>
    <age>15</age>
    <gender>male</gender>
  </user>
  <user id='2'>
    <name>Li Si</name>
    <age>14</age>
    <gender>male</gender>
  </user>
</users>

string fileName =@"D:\";
      XmlDocument xmlDoc = new XmlDocument();
      XmlNode header = ("1.0","utf-8",null);
      (header);
      //Create a first-level node      XmlElement rootNode = ("users");
      List<User> list = GetUsers();
      foreach (var item in list)
      {
        XmlElement xn = InserUser(item,xmlDoc);
        (xn);
      }  
      (rootNode);
      (fileName);
    }
    /// <summary>
    /// Create the entire user element    /// </summary>
    /// <param name="user"></param>
    /// <param name="xmlDoc"></param>
    /// <returns></returns>
    private static XmlElement InserUser(User user, XmlDocument xmlDoc)
    {
      XmlElement xn = ("user");
      ("id",  + "");
      (GetXmlNode(xmlDoc,"name",));
      (GetXmlNode(xmlDoc, "age",  + ""));
      (GetXmlNode(xmlDoc, "gender", ));
      return xn;
    }
    private static XmlElement GetXmlNode(XmlDocument xmlDoc,string name,string value)
    {
      XmlElement xn = (name);
       = value;
      return xn;
    }
    private static List<User> GetUsers()
    {
      List<User> list = new List<User>();
      for (int i = 0; i < 10; i++)
      {
        User user = new User();
         = i;
         = "Name" + i;
         = 15;
         = "male";
        (user);
      }
      return list;
    }

Write XML

class User
  {
    public int Id { set; get; }
    public string Name { get; set; }
    public int Age { get; set; }
    public string Gender { set; get; }
    public override string ToString()
    {
      return Id +","+Name + "," +Age+"," + Gender;
    }
  }

Entity