I would start by reading the user guide. That is assuming after one has read about VPNs on the net - there are many good white papers and explanations via google.
I've setup VPNs on Draytek routers, never on these netgear ones, it seems totally different.
How do you choose which dials which? How does the IP/FQDN identification work?
I've searched the internet but all I can find is demo's of setting up the netgear prosfae client doftware, I can't find any walkthroughs of a LAN to LAN VPN