Ok this is the way to set it up. From a post I made week or so ago.
Connect the new netgear to one PC without any other network connection, just that one PC and the NG router. From Lan port on PC to LAN port on router (Do not use the Internet (WAN) Port on the router).
Open a Web browser and type in 192.168.1.1, username is admin and password is password. Once you have the router setup pages displayed go into the Advanced section and then Advanced Setup. In the Wireless setup Uncheck "Enable Routers Pin" and put a check in "Keep Existing Wireless Setting and click Apply. Then close that area and go to the Setup area in that same list on the left then Wireless Setup. Enable SSID, Type in a Name for your wireless network and then select WPA2-PSK (AES) as the security. Then type in a Password you want to use and then "WRITE IT DOWN" then click Apply.
Once you have that done go to the LAN setup section, same list. For the IP address of the router type in 192.168.1.253 (that will make sure the NG router is out of the ATT router LAN DHCP pool). Then Uncheck "Use Router as DHCP Server and again click Apply. At this point you may lose the connection with the router and you may have to set a Static IP on the computer to something like 192.168.1.(from 1 to 252). Then you will need to type in the new router IP address, 192.168.1.253, and log back in to it. Now go to the Advanced section again and then to Administration and change the routers password, AND WRITE IT DOWN. You will then need to log back in. Once that is all done connect from the ATT router LAN port to a LAN port on the NG router (Do Not Use the WAN/Internet port on the NG). you will need to reset the PC you were using to Obtain IP auto and reconnect that PC back to your home LAN.
That should do it. All wireless devices should now see the SSID you set and all you have to do is type in the wireless password to connect.