what version of c&c to play friend online do i need

Me and my friend are very interested to know what version of command and
conquer do you need in order to be able to play each other online. Also is
there instructions with it how to set a connection up the proper way as i
was a bit confused with generals , and if not could you please tell me what
i open and set up and also does my friend do the same or does he do a
different set up from me for us to play one on one. It would be so much
appreciated if you could help me out on this with some advice on what i must
do and what version to have , Thanks.