What do I need to do to become a private drum teacher?

How to play the drums seems like a good start.  Sorry, but you know
everyone was thinking that.

Clearly playing the drums would be a good start!!! The question
wouldn't have been asked if I couldn't. I was wondering if you had to
have a set qualification or if you could just teach?

just put out a local listing advertising drum lessons. there are a
fair amount of internet sites you can register with to get your name
out there and show up in searches.