There are classes you can take... or you can go to a lot of births for free to gain experience.
at 3:31 PM on Mar. 15, 2009
Go to DONA.com, childbirthinternational.com or there are a few others that you can do most stuff online. Also if you are in a bigger city (and some smaller ones) call your local hospital L&D and see if they have an intern program for doula's some will help you get certified and ask that you volunteer for them for free or a discounted rate for a while. I called and talked to some doula's in my area and they weere really helpful, telling me how to get started and such. Good luck!