C# WinForm向服务器发送文件

using System;
using System.Windows.Forms;
using System.IO;
using System.Net;

namespace WindowsFormsApplication3
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            string uriString = "111.115.42.99";
            string  fileNamePath = "D:\\1.txt";
            WebClient myWebClient = new WebClient();
            FileStream fs = new FileStream(fileNamePath, FileMode.Open, FileAccess.Read);
            //FileStream fs = OpenFile();
            BinaryReader r = new BinaryReader(fs);
            try
            {
                //使用UploadFile方法可以用下面的格式
                //myWebClient.UploadFile(uriString,"PUT",fileNamePath);
                byte[] postArray = r.ReadBytes((int)fs.Length);
                Stream postStream = myWebClient.OpenWrite(u