You posted in the Access Server question, so I assume you are using that product. I'll suggest you read the documents on
http://openvpn.net/index.php/access-server/docs.html. Its quite simple, but since you haven't read anything its as easy as going into the web ui and changing the setting "Should client Internet traffic be routed through the VPN?"
If you are using DNS behind the VPN for your remote clients then you'll have to keep tunneling the traffic over the VPN