it depends on the language that you are using
if you were using VB
uses the syntax Winsock1.SendData("HELO")
You'd need to add carriage return line feeds as well.
but I can see that you are using C, and the code is.
just cause I feel it makes it easier to debug,
msgString = "HELO\r\n";
msgStringLen=strlen(mgsString); /* Determine input length */
/* Send the string to the server */
if (send(sock,msgString,msgStringLen, 0) !=msgStringLen)DieWithError("send() sent a different number of bytes than expected");