将标头添加到服务器/客户端连接

我需要翻译此代码以添加一个大的字节序 2 字节标头。它现在可以在没有标题的情况下工作，但我对如何添加它有点迷茫。

TcpClient client = new TcpClient(ipNum, portNum);
NetworkStream nw = client.GetStream();
byte[] send = Encoding.UTF8.GetBytes(userInput);
Console.WriteLine("Sending : " + userInput);
nw.Write(send, 0, send.Length);
byte[] readBytes = new byte[client.ReceiveBufferSize];
int bytesRead = nw.Read(readBytes, 0, client.ReceiveBufferSize);
Console.WriteLine("Received : " + Encoding.UTF8.GetString(readBytes 0, readBytes);