.net background thief program

private void Page_Load(object sender, System.EventArgs e)
  {
  
   WebRequest wreq=WebRequest.Create("http://weather.yahoo.com/forecast/CHXX0133_c.html"); 
 
   HttpWebResponse wresp=(HttpWebResponse)wreq.GetResponse(); 
 
   string HTML =""; 
   Stream s=wresp.GetResponseStream(); 
 
   StreamReader objReader = new StreamReader(s,System.Text.Encoding.GetEncoding("GB2312")); 
 
 
   string sLine = ""; 
   int i = 0; 
 
   while (sLine!=null) 
   { 
    i++; 
    sLine = objReader.ReadLine(); 
    if (sLine!=null) 
     HTML += sLine; 
   } 
 
   String temp= ""; 
   int start,stop; 
 
  // string aa="<div class="five-day-forecast night" style="border:none;">";
  
  //string aa="<div class="five-day-forecast" style="border:none;">";

   string aa="<table><th>Today</th>";
   start = HTML.IndexOf(aa,0,HTML.Length); 
 
   stop = HTML.IndexOf("</table>",start)+8; 
       
 
   temp = HTML.Substring(start, stop - start); 

   this.Weather2.Text=temp;
      string cc="<tr class="titles"><td>";
//    
       int aa1 =temp.IndexOf(cc,0,temp.Length);

   int bb=temp.IndexOf("</td>",aa1);

   this.Weather2.Text=temp.Substring(aa1, bb - aa1).ToString(); 
  
 
   string ee="<tr class="temps">";

   int aa2 =temp.IndexOf(ee,0,temp.Length);

   int bb1=temp.IndexOf("</td>",aa2);

   this.Label1.Text=temp.Substring(aa2, bb1 - aa2).ToString(); 

  
   // 在此处放置用户代码以初始化页面
  }