how to receive file from clients and save file on server in c#

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.Net.Sockets;
namespace client
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            OpenFileDialog ofd = new OpenFileDialog();
           ofd.ShowDialog();
           textBox1.Text = ofd.FileName;
}

        private void button2_Click(object sender, EventArgs e)
        {
            Stream Fs = File.OpenRead(textBox1.Text);
           Byte[] buffer = new Byte[Fs.Length];
         Fs.Read(buffer, 0, buffer.Length);
          TcpClient socket = new TcpClient("10.10.3.137", 10);
         NetworkStream nw = socket.GetStream();
        nw.Write(buffer, 0, buffer.Length);
        nw.Close();
        } 
        }
    }