where do i find the wps pin for my printer

The pin is made by the printer, not printed anywhere. On the printer panel go to Wireless or Network setup, then Wi-Fi Protected Setup, then PIN. It shows an 8 digit code on the screen or prints it on a page and it's valid for about two minutes. Type that into the router's WPS pin box. Honestly though, the push button method or just the HP Smart app is less fiddly, the app finds the printer over bluetooth and hands it your wifi password.