There are a few places you can get qualified. I think bb has an article on this if you have a look. It lists different places in each state. Can't link you because I'm on my phone.
I did my course through the Australian doula college. At this stage it's the only one that does an actual government recognised certificate. You don't actually need that but you can get study allowance when doing the course.
Being a doula is very much a intuition type thing I find. You learn all the information, but in the end, every birth is different and every mother will need different from you.

Hope that helps, good luck. X