This one’s applicable to what you’re doing.
http://www.soundonsound.com/sos/apr10/articles/acguitar.htm
We did an extensive guitar recording thread on the forum. This should shortcut all the questions you’re going to ask. Have a read through this. I believe it’s still the longest thread on the forum.
https://forum.audacityteam.org/t/budget-usb-mic-for-classical-guitar-recording-needed/12367/1
Koz