Setting up a VPN using PPTP protocal can be vulnerable for security. Yet it is an easy and quick way to set up a virtual private network (VPN).
The procedure to setup up a PPTP VPN server can be found here: https://help.ubuntu.com/community/PPTPServer
The way to connect to a PPTP server on a client machine can be found here: https://my.hostvpn.com/knowledgebase/19/Setup-a-PPTP-VPN-Connection-in-Linux-Ubuntu.html