Availability VPN from both sides

Hello,
I have one that has a MK1 public IP and bears PPTP VPN server, then I MK2 who has public IP and bears PPTP client that is connected to the first MK.
How can I order I got from MK1 to MK2? I do not need to get into feeling that is behind the MK2 but only at the very MK2.
Thanks.