separate vocal track while listening to mix

Hi, new to audacity. trying to record vocal track alongside mp3 track. I cannot get a separate track for vocal to record without the backing track recording with it. If I mute one the other goes off.

Make sure to select your microphone as your [u]Recording Device[/u]. (Do NOT choose “Stereo Mix” or “Loopback”.)

And, I assume you are monitoring with headphones?

Hi, many thanks for responding. My settings there are MME Microphone s 2 (stereo) speakers sbx. is this correct? Lee

and yes monitoring with headphones. lee