winform 里 如何实现文件上传

看了网上写的 用webclient类的uploadfile方法，

我在本地建立了个webform,winform窗体,  现在可以本地实现文件传递，可以选择文件传到d:\temp路径下，但怎们传到服务器上就不会了

求教大神

webform code

 using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Web;
 using System.Web.UI;
 using System.Web.UI.WebControls;

 public partial class SiteMaster : System.Web.UI.MasterPage
 {
     protected void Page_Load(object sender, EventArgs e)
     {
         foreach (string f in Request.Files.AllKeys)
         {
             HttpPostedFile file = Request.Files[f];
             file.SaveAs(@"D:\Temp\" +file.FileName);
         }
         if (Request.Params["testKey"] != null)
         {
             Response.Write(Request.Params["testKey"]);
         }
     }
 }

winform code:

 using System;
 using System.Collections.Generic;
 using System.ComponentModel;
 using System.Data;
 using System.Drawing;
 using System.Linq;
 using System.Text;
 using System.Windows.Forms;
 using System.IO;
 using System.Net;
 using System.Web;

 namespace 上传
 {
     public partial class UpLoadForm : Form
     {
         public UpLoadForm()
         {
             InitializeComponent();
         }
         private void btn_select_Click(object sender, EventArgs e)
         {
             OpenFileDialog ofd = new OpenFileDialog();
             ofd.Multiselect = true;
             if (ofd.ShowDialog() == DialogResult.OK)
             {
                 this.txtpath.Text = ofd.FileName;
             }
         }
         private void btn_Upload_Click(object sender, EventArgs e)
         {
             if (this.txtpath.EditValue != null)
             {
                UpLoadFile("http://localhost:61750/WebSite3/Default.aspx", "POST", this.txtpath.Text.Trim());
                // UpLoadFile("\\192.168.5.71", "POST", this.txtpath.Text.Trim());
             }
             else
             {
                 MessageBox.Show("请选择上传文件");
             }

         }
         public void UpLoadFile(string Serverpath, string Mode, string Localpath)
         {
             try
             {
                 WebClient mywebcilent = new WebClient();
                 mywebcilent.UploadFile(Serverpath,Mode,Localpath);
                 MessageBox.Show("上传成功");
             }
             catch
             {
                 MessageBox.Show("上传失败");
             }
         }

     }
 }