your question is quite hard to answer , you need to do it yourself or going here to learn
https://forums.openvpn.net/viewforum.php?f=16 after that you must do all of them and if something wrong come back here so people can help you .
when openvpn use more than one person so that is for commercial purport so consider going to openvpn access server is easy for you to management user than community version