When you have two offices connected using LAN to LAN over VPN, how does a computer user connect to a file server in the other office?

I understand how to create and use a VPN connection from my Mac. But I want to set up the office so that our Vigor router is making the VPN connection. That is set up and it says its connected. So does the VPN server at the other end (in this case Mac OS X Server).

Normally we use "connect to server" and give the address of the server on the other subnet at the remote office. That doesn't work when the Vigor is creating the VPN.

What am I missing?

Thanks!