c# novice server send multiple clients

i am c# novice and am writing server send multiple clients. i am able to send to single client however not able to multiple clients.
server code
 

namespace server2
{
    public partial class server2 : Form
    {
     List<tcpclient> _clients = new List<tcpclient>();
        _clients.Add(client1);
       _clients.Add(client2);
 
        public server2()
        {
            InitializeComponent();
        }
 
        private void server2_Load(object sender, EventArgs e)
        {
           byte[] bt;
           bt = new byte[] { 127,0,0,1 };
           IPAddress address = new IPAddress(bt);
    
           byte[] bt;
           bt = new byte[] { 127,0,1,1 };
           IPAddress address = new IPAddress(bt);         
        }
 

        private void send_Click(object sender, EventArgs e)
        {
            foreach (TcpClient client in _clients)
            {
                NetworkStream stream = client.GetStream();
                BinaryWriter bwrite = new BinaryWriter(stream);
                bwrite.Write(txtServer.Text);  
            }
 
        }
 
       
        private void add_Click(object sender, EventArgs e)
        {
            TcpClient client = new TcpClient();
            string ipAddress = txtClientAddress.Text;
            client.Connect(ipAddress, PORT);
            _clients.Add(client);
            txtClientAddress.Text = "";
            
        } 
         
        
  }
}

 

[edit]Code block added - OriginalGriff[/edit]