Questions about entering the education field from outside major

I'm an American currently living in South America. I studied Accounting in college and worked in accounting for 3 years and wasn't very taken by it. I moved to South America to volunteer at an orphanage and think about what I wanted to do, and I got placed in a kindergarten as an assistant to the Teacher. I've been here for almost 2 years now and got hired as a 6th grade teacher at an international school and am looking into doing it long term, but I would need a master's to continue in the field if I return to the states.

My friend suggested looking for online degree programs but I really don't even know where to start. Would I have needed to study something education related in order to get into a master's program? Or a licensure program? I hate this idea that I'm stuck to business related career choices. Thanks for any advice anyone can give me.