It is easy to configure and connect two Small Office/Home Office (SOHO) broadband routers together.
Configure the IP address of the secondary router to be in the same subnet as the primary router, but out of the range of the DHCP server in the primary router. For instance if the DHCP server addresses 192.168.0.2 through 192.168.0.100, then assign the secondary router 192.168.0.254 as it's IP address. Disable the DHCP server in the secondary router.
Setup the wireless section in the secondary router just the way you would if it was the primary router.
Connect from the primary router's LAN port to one of the LAN ports on the secondary router. If there is no uplink port and neither of the routers have auto-sensing ports, use a cross-over cable. And last, but not least, leave the WAN port of the secondary router unconnected!
Now the primary router handles the Internet connection and dishes out DHCP IP addresses to the whole LAN and it is only necessary to set up port-forwarding once on the primary router. The secondary router is acting as a switch and if wireless capable, with attached Wireless Access Point (WAP).