Here's a good place to start:
http://train.apple.com/certification/
As far as working on macs, it's definitely a niche industry and there's not much demand for techs in the field the way there is for PC/Microsoft Certified techs, but there are still ways to make money doing it.
Go in and talk to someone at your local apple store for more info and see if you have any certified stores in your area (not an apple store) that need someone with the skills you are going to acquire.
Lastly, focus on creative and design firms who use macs excluslively; we're notorious for loving macs but not being able to work on them when things go wrong. This doesn't apply to me, of course.
I'm a Junior IT at this point since I hate depending on anyone to fix my computer for me.