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: emp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");
            } 
        }

    
    }
}