简单的 Web 服务器 C#

我需要一些关于这段代码的帮助：

using System;
using System.Collections.Generic;
using System.Net;
using System.Net.Sockets;
using System.IO;
namespace HttpEcho
{
  class HttpEchoProgram
  {
    static void Main(string[] args)
    {
      TcpListener server = new TcpListener(IPAddress.Parse("127.0.0.1"), 80);
      server.Start();
      Console.WriteLine("Waiting for Client...");
      TcpClient newConn = server.AcceptTcpClient();
      IPEndPoint iep = (IPEndPoint)(newConn.Client.RemoteEndPoint);
      IPAddress add = iep.Address;
      int prt = iep.Port;
      Console.WriteLine("Connected with a client: {0}: {1} ", add, prt);
      NetworkStream stream = newConn.GetStream();
      StreamReader sr = new StreamReader(stream);
      StreamWriter sw = new StreamWriter(stream);
      sw.WriteLine("HTTP/1.1 200 OK");
      sw.WriteLine("Content-Type: text/plain");
      //sw.WriteLine("Content-Length: size");
      sw.WriteLine();
      String line = null;
      while ((line = sr.ReadLine()).Length != 0)
      {
        Console.WriteLine(line);
        sw.WriteLine(line);
        sw.Flush();
      }
      newConn.Close();
      server.Stop();
    }
  }
}

我想修改此代码，以便它可以用作简单的 Web 服务器，它在本地文件系统中获取请求的页面并将其返回到浏览器。