ENDIAN Firewall - Setting up Home Network

I am trying to set up an Endian Fire Wall server in my home. I have taken an old computer with two networking cards, and what I am trying to do is have my one green output go to a D-Link router which the rest of my home devices will be accessing. While I haven't had trouble getting the red input to work (my ISP just uses DHCP) I am having trouble getting the green output to work with my router. I am very new to working with networks and not a professional and so I am not sure what settings I need to change to make the router and the Endian PC work together properly. Right now I have the IP for the Endian PC set at the default of 192.168.0.15 and my router is set to work with DHCP. Do I need to set up a static route? Also when I try to plug my VISTA home PC directly into my one green ouput it appears as an unidentified network to the VISTA PC and does not allow internet access.