It sounds like you want to use it as a wireless bridge. Many "home use" wireless routers don't support this.
In any case you don't want two routers in their default configuration on the same network. They both will try to hand out DHCP leases and claim to be the default gateway. However, since only one has an internet connection if you get an IP from the other one it won't work. You should turn off the routing and DHCP functions of the second router.
But it is possible to convert a router to a bridge. See here: http://www.makeuseof.com/tag/how-to-tur ... ss-bridge/