You can use Netgear Installation Assistant for Netgear Wi-Fi Extender Setup. Steps to perform the setup for Netgear extender via installation assistant are:
1.Connect the home router with the extender.
2.On your device, go to a web browser.
3.Now visit www.mywifiext.com, here you will see Netgear installation assistant.
4.To connect the extender with the existing Wi-Fi network, follow the prompt.
5.Now, plug in the extender to an electrical outlet. 
6.Reconnect the computer to the new extender. 
7.Plug the extender into an electrical outlet and wait until the Power LED turns green.
Read More
how to update routers firmware