socket 多个客户端异步发送数据，服务端如何接收数据，并保存下来

     现在问题是多个客户端异步发送数据，服务端如何接收数据，我现在能实现功能是一个客户端发送数据，服务端就接收。客户端是一个TextBox，里面输入数据，点击发送。服务端就是一个Textbox。接收。但是出现第一个问题是：如何把客户端每次发来的数据都保存到记事本里。
下面是我的代码using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Net;
using System.Net.Sockets;
using System.Threading;
using System.IO;namespace 接收
{
    public partial class Form1 : Form
    {
        public static string data = null;
        public Socket Client;
        public Form1()
        {
            Form.CheckForIllegalCrossThreadCalls = false;
            InitializeComponent();
            Listen();
           
           
        }
                public Thread myThread;            
                public Socket newsock;              
                public IPEndPoint localEP;        
                public int localPort;
                
                //用来设置服务端监听的端口号
                public int setPort                        
                {
                        get { return localPort; }
                        set { localPort = value; }
                }
                
               
                //监听函数
                public void Listen()
                {    
                        //设置端口
                        setPort=6000;
                        //初始化SOCKET实例
                        newsock = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
                        //初始化终结点实例
                       
                            IPAddress ServerIP = IPAddress.Parse("128.1.2.251");
                            IPEndPoint localEP = new IPEndPoint(ServerIP, 6000);
                       
                        try
                        {
                                //绑定
                                newsock.Bind(localEP);
                                //监听
                                newsock.Listen(10);
                                //用于设置按钮状态
                                m_Listening = true;
                                newsock.BeginAccept(new AsyncCallback(OnConnectRequest), newsock);
                               
                         }
                        catch (Exception ex)
                        {
                            MessageBox.Show(ex.Message);
                        }                                      }
                //当有客户端连接时的处理
                public void OnConnectRequest(IAsyncResult ar)
                {
                     //初始化一个SOCKET，用于其它客户端的连接
                        Socket server1 = (Socket)ar.AsyncState;
                        Client = server1.EndAccept(ar);
                        //将要发送给连接上来的客户端的提示字符串
                        string strDateLine = "Welcome here";
                        Byte[] byteDateLine = System.Text.Encoding.ASCII.GetBytes(strDateLine);
                        //等待新的客户端连接
                        server1.BeginAccept(new AsyncCallback(OnConnectRequest), server1);
                                int recv = Client.Receive(byteDateLine);
                                string stringdata =  Encoding.ASCII.GetString(byteDateLine, 0, recv);
                                DateTimeOffset now = DateTimeOffset.Now;
                                //获取客户端的IP和端口
                                string ip = Client.RemoteEndPoint.ToString();
                                if (stringdata == "STOP")
                                {
                                        //当客户端终止连接时
                                       Console .WriteLine(ip+"已从服务器断开");
                                        
                                }
                                //显示客户端发送过来的信息
                               this.textBox1 .Text = stringdata ;
                      //目前我是用this.textbox1来接收的。但是，客户端变数据，服务端就清空也变数据，没法保存上次传过来的数据。                               
                                           
                }       
           
              
                //窗口关闭时中止线程。
                private void Form1_FormClosing(object sender, FormClosingEventArgs e)
                {
                        if (myThread != null)
                        {
                                myThread.Abort();
                        }
                                       }
      
        }
}