Log in to your router using the wired PC. You'll need to type in the router's IP address in IE address bar. Search google for this and for the default name and password, if not changed, unless you know the details.
Once logged in select wireless network settings, or similar, make a note of the security mode (ie WPA2-PSK) and copy exactly the the pre-shared key. Also note the SSID (name that the router is broadcasting under). Log out of the router.
On your laptop select 'connect to' and select your router. Follow prompts to enter the details.