PLEASE HELP! Audacity Isn't Detecting Sound From My Mic

I’m struggling with an Audio Technica microphone. It’s plugged into a Steinberg CI 1 Yamaha USB interface but Audacity isn’t picking it up. The built-in mic on my computer picks up sound but I’m trying to record guitar and vocals so I require a separate microphone so that the guitar doesn’t overpower my voice. I tried various selections using the drop down bars but nothing’s working. Any idea what this could mean or alternative solution?

The only correct input choice is the USB Audio CODEC for the Yamaha.

If you don’t see that choice in Audacity, use Transport > Rescan Audio Devices in the Audacity Menu Bar at the top. If you connect a USB device after Audacity is running, you need to rescan or to restart Audacity.