Go into Windows Control Panels > Sound and make sure your Microphone connection is selected and turned up if there’s a volume control.The panel might be selecting the built-in microphone if you have one of those.
Then launch Audacity and go into Edit > Preferences > I/O and make sure the same thing is selected.
While you’re in there, change the quality from 32-Floating to 16 bit. Close Audacity and restart it to make the settings stick.
Click once in the red record meters and they should wake up and meter whatever sound you have going through the mixer. Your meters may look different…
http://kozco.com/tech/audacity/Audacity1_record.jpg
Get all that so far?
Press record.
Now the bad news. You don’t have a high-level, Stereo Line-In connection and the Mic-In is mono and very, very sensitive. So instead of getting a stereo performance with instruments on the left and right, you will get left only, or possibly two channels with left sound on both. Even that’s good news. You might also not be able to do this at all because of distortion or crunchy sound. You will be overloading the microphone connection some thousand or so times and very few people manage to get good sound past that.
Windows laptops are aggressively business computers and audio production sometimes suffers. What you’re doing would work perfectly fine on a large Deskside PC or a Mac. You can add a USB sound device to your machine and do it that way.
https://forum.audacityteam.org/t/sound-card-reviews/8375/1
Koz