PPTP stands for point to point tunneling protocol, it is a microsoft implementation that can be encrypted up to 128bit for Virtual Private Networks. In order to better integrate linux and unix with the more prevalent Windows world Implementations of PPTP clients and a server Version called PoPToP have been developed. It is relatively easy to set up and works relatively well for a Microsoft concept.
As for where to find information Sourceforge has documentation on setting up clients on the PPTP client page, though I cannot recall the software name at this time though it includes PPTP, do a search at sourceforge. Some of the documentation for PoPToP might be useful as well though it is a server Daemon. YOu may have to patch your kernal to get the higher encryption, that the server will probably need, however, newer versions od PPP negate the need to patch Kernals, if you perform a search for VPN and or PPTP on this forums site you should at least come across posting I have put forth previously as well as others;And a search on dogpile for linux pptp should yields some excellent results as well. Good luck please let me know how it goes and if I can assist further.