|For simplicity's sake your best option is to completely replace the wired router with the wireless router. |
The above is excellent advice and is the way I would do it myself.
However, if for some reason you absolutely have to connect the wireless router to the wired router, you will want to click on my name above in this response and read my “how-to” guide titled, “Add a second Router to your LAN”
If you decide to add instead of replace, you will want to pay attention to the version where you interconnect the two router's "LAN port to LAN port". You will also want to disable DHCP on the wireless router. Do use WPA2 encryption on your WLAN.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.