Save and Load from XML help

I found this code at www.unifycommunity.com which allows you to save the X, Y and Z positions of the player.

 using UnityEngine; 
 using System.Collections; 
 using System.Xml; 
 using System.Xml.Serialization; 
 using System.IO; 
 using System.Text; 
 
 public class _GameSaveLoad: MonoBehaviour { 
 
    // An example where the encoding can be found is at 
    // http://www.eggheadcafe.com/articles/system.xml.xmlserialization.asp 
    // We will just use the KISS method and cheat a little and use 
    // the examples from the web page since they are fully described 
     
    // This is our local private members 
    Rect _Save, _Load, _SaveMSG, _LoadMSG; 
    bool _ShouldSave, _ShouldLoad,_SwitchSave,_SwitchLoad; 
    string _FileLocation,_FileName; 
    public GameObject _Player; 
    UserData myData; 
    string _PlayerName; 
    string _data; 
     
    Vector3 VPosition; 
     
    // When the EGO is instansiated the Start will trigger 
    // so we setup our initial values for our local members 
    void Start () { 
       // We setup our rectangles for our messages 
       _Save=new Rect(10,80,100,20); 
       _Load=new Rect(10,100,100,20); 
       _SaveMSG=new Rect(10,120,400,40); 
       _LoadMSG=new Rect(10,140,400,40); 
         
       // Where we want to save and load to and from 
       _FileLocation=Application.dataPath; 
       _FileName="SaveData.xml"; 
     
       // for now, lets just set the name to Joe Schmoe 
       _PlayerName = "Joe Schmoe"; 
         
       // we need soemthing to store the information into 
       myData=new UserData(); 
    } 
     
    void Update () {} 
     
    void OnGUI() 
    {    
        
    //*************************************************** 
    // Loading The Player... 
    // **************************************************       
    if (GUI.Button(_Load,"Load")) { 
        
       GUI.Label(_LoadMSG,"Loading from: "+_FileLocation); 
       // Load our UserData into myData 
       LoadXML(); 
       if(_data.ToString() != "") 
       { 
         // notice how I use a reference to type (UserData) here, you need this 
         // so that the returned object is converted into the correct type 
         myData = (UserData)DeserializeObject(_data); 
         // set the players position to the data we loaded 
         VPosition=new Vector3(myData._iUser.x,myData._iUser.y,myData._iUser.z);              
         _Player.transform.position=VPosition; 
         // just a way to show that we loaded in ok 
         Debug.Log(myData._iUser.name); 
       } 
     
    } 
     
    //*************************************************** 
    // Saving The Player... 
    // **************************************************    
    if (GUI.Button(_Save,"Save")) { 
               
      GUI.Label(_SaveMSG,"Saving to: "+_FileLocation); 
      myData._iUser.x=_Player.transform.position.x; 
      myData._iUser.y=_Player.transform.position.y; 
      myData._iUser.z=_Player.transform.position.z; 
      myData._iUser.name=_PlayerName;    
           
      // Time to creat our XML! 
      _data = SerializeObject(myData); 
      // This is the final resulting XML from the serialization process 
      CreateXML(); 
      Debug.Log(_data); 
    } 
     
     
    } 
     
    /* The following metods came from the referenced URL */ 
    string UTF8ByteArrayToString(byte[] characters) 
    {      
       UTF8Encoding encoding = new UTF8Encoding(); 
       string constructedString = encoding.GetString(characters); 
       return (constructedString); 
    } 
     
    byte[] StringToUTF8ByteArray(string pXmlString) 
    { 
       UTF8Encoding encoding = new UTF8Encoding(); 
       byte[] byteArray = encoding.GetBytes(pXmlString); 
       return byteArray; 
    } 
     
    // Here we serialize our UserData object of myData 
    string SerializeObject(object pObject) 
    { 
       string XmlizedString = null; 
       MemoryStream memoryStream = new MemoryStream(); 
       XmlSerializer xs = new XmlSerializer(typeof(UserData)); 
       XmlTextWriter xmlTextWriter = new XmlTextWriter(memoryStream, Encoding.UTF8); 
       xs.Serialize(xmlTextWriter, pObject); 
       memoryStream = (MemoryStream)xmlTextWriter.BaseStream; 
       XmlizedString = UTF8ByteArrayToString(memoryStream.ToArray()); 
       return XmlizedString; 
    } 
     
    // Here we deserialize it back into its original form 
    object DeserializeObject(string pXmlizedString) 
    { 
       XmlSerializer xs = new XmlSerializer(typeof(UserData)); 
       MemoryStream memoryStream = new MemoryStream(StringToUTF8ByteArray(pXmlizedString)); 
       XmlTextWriter xmlTextWriter = new XmlTextWriter(memoryStream, Encoding.UTF8); 
       return xs.Deserialize(memoryStream); 
    } 
     
    // Finally our save and load methods for the file itself 
    void CreateXML() 
    { 
       StreamWriter writer; 
       FileInfo t = new FileInfo(_FileLocation+"\\"+ _FileName); 
       if(!t.Exists) 
       { 
          writer = t.CreateText(); 
       } 
       else 
       { 
          t.Delete(); 
          writer = t.CreateText(); 
       } 
       writer.Write(_data); 
       writer.Close(); 
       Debug.Log("File written."); 
    } 
     
    void LoadXML() 
    { 
       StreamReader r = File.OpenText(_FileLocation+"\\"+ _FileName); 
       string _info = r.ReadToEnd(); 
       r.Close(); 
       _data=_info; 
       Debug.Log("File Read"); 
    } 
 } 
 
 // UserData is our custom class that holds our defined objects we want to store in XML format 
  public class UserData 
  { 
     // We have to define a default instance of the structure 
    public DemoData _iUser; 
     // Default constructor doesn't really do anything at the moment 
    public UserData() { } 
     
    // Anything we want to store in the XML file, we define it here 
    public struct DemoData 
    { 
       public float x; 
       public float y; 
       public float z; 
       public string name; 
    } 
 }

I'm making a game that does autosave when the player reaches a checkpoint. I want to edit the code so it saves:

• The checkpoint the player is at instead of the X, Y and Z.

• The player's health

• The amount of ammo the player has

• The player's XP/Level

Can you help me please?