Alright, I hate to admit this because I don't like incorporating it into my identity but technically I'm certified to teach school in my state. I didn't go through with it because it wasn't for me, but I certainly got an inside view of how you become a teacher.
The first thing I need to tell you is that it is not hard to become a teacher (but it is hard to be a teacher because the system is pretty messed up and the kids need more than anyone is giving them for the most part). First of all, you need a Bachelor's degree. That's a four year degree, but it can be in anything, you have to go through these stupid courses which are a lot like driver's ed, and you need to take a competency test for the subject you want to teach. Then you need to take what's called a pedagogy exam, and then you can get hired as a teacher.
Once you get hired as a teacher it is very difficult for them to fire you, they can send you to another school, they can send you to be some kind of administrator, but they really have to put their asses on the line to fire you and it may not work even in the most straightforward and egregious of cases.
I want to make a point here about the special ed thing, it may not have been your idea to be a special ed teacher at all. The school will find a teacher who is underutilized and assign them to teach another subject which needs a teacher. (This why my anatomy and physiology class was taught by our soccer coach, and why my friend's dad who has a master's degree in history was asked to teach P.E.). They will give you plenty of time to take the competency test, you can teach for a long time without it before they start worrying about being in compliance with the No Child Left Behind Act.
Your special ed teacher may not have a degree in teaching special ed at all, they could just as easily be a big dude with a degree in geography or clarinet, or whatever.
Before I go, I'm going to let you look at the competency tests for my state (Texas)
TExES exam.