Just wiped my iMac clean and want to reinstall OS. It says I’m not connected to the internet. Duh! I just wiped all my wi-fi info. What do I do?

You may not be able to use wifi connection. Connect using ethernet cable for initial setup.

What year model iMac?

What macOS version was it on?

Plug in a USB keyboard and mouse, then try starting up in macOS Recovery mode.

go to > Use macOS Recovery on an Intel-based Mac - Apple Support and enter the macOS version that it came with or that it was running when you erased it.