How to use external microphones to sing on Smule App

Hello guys! First of all, thanks so much for the 50K views on this video https://www.youtube.com/watch?v=kagBguAxOBg&t=8s which is how to use microphones to sing on Smule. Honestly, I wish I can make a new video for a more in-depth instructions on how to use it but I think a blog would be a lot helpful...