EFW Support

We have this netsite which can be accessed from our network properly (netsite sees that the connection is from our efw's ip address). Now I should config VPN connection so that the same could be done outside our network also. Open VPN connection to our efw which then forwards the traffic to this specific netsite so that the netsite recognizes that traffic is coming from our ip address. I've managed to create the open VPN connection e.g. using it I can access efw config page. What I don't know is how to forward the traffic the way I explained. I've tried many many things and ran out of imagination. I have feeling that this isn't that hard problem but I'm quite a newbie with VPN, well with efw also :D I'd be very grateful if someone could at least point me to right direction. Thanks  :)