Sharing of files over the internet

[Degas]

My friends and I are trying to create a network over the internet, so we can access each other computer's over the net, anyone knows how to do this or can maybe give me some tips? We don't even know if what we are trying to do is a VPN (virtual private network) or if it's actually an extranet so it's really hard to find out for us how to do it, any help would be greatly appreciated. :)

[Greenstead]

It would not be an extranet.

The worst thing you could do is to use wndows sharing like you would in a LAN because that invites hackers in.

It has to be a VPN type solution. That could prove expensive/complex with commercial solutions. The most suitable, I would suggest, is UltraVNC (free) which is a remote desktop tool but also allows file search and transfer between PCs over LAN or Internet. It also has authentication and encryption which is essential when used over the internet. It does not require port forwarding through routers or ICS.
See here:
http://ultravnc.sourceforge.net/

Encryption plugins are being developd. Try one.
http://home.comcast.net/%7Emsrc4plugin/