That is not a C# error.. It's actually an IRC error, which means you connected to the server. You need to do a few commands so that you can login/etc.
Example:
USER Veeresh Veeresh :Veeresh Veeresh\r\n
NICK Veeresh\r\n
JOIN #quakenet\r\n
PRIVMSG #quakenet :Hey, what's up\r\n