I'm assuming you mean "UDP".
byte[] data = new byte[1024];
string sData = "<the packet data - fill with what you want>";
IPEndPoint ep = new IPEndPoint("127.0.0.1", 8000); // change to the IP address and port of your server
Socket gameServer = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
data = Encoding.ASCII.GetBytes(sData);
gameServer.SendTo(data, data.Length, SocketFlags.None, ep);
Of course, there are all sorts of things that can go wrong - you need to put in exception handling to make sure you catch any issues.
Now, if your data is not string data and is already binary, well, you can just serialize the data into the byte array and send it along.