I train my own horses. Yes, I did teach myself how to train. Mostly by experience, books and magazines. I had some help from a local trainer, but his methods are a little too crazy for my liking.
Training is no easy job when you don't know exactly what to do and don't have someone who knows the exact situation you are in to help you. If you get stuck or lost you have to figure out how to do it on your own. There was a point when I believed I could train a young horse all by myself. However, I didn't know the begining of it. I had no idea what lateral flexion was or how to get the correct lead. The thing is You don't know how much you don't know until you know it.
If I would have gotten a young horse at that time I would have not been capable of training it.
My advice: yes you can teach yourself and don't be scared of my story. I don't know how much you already know, but I would still recommend searching for all the information you can get. Books are great. I learned a lot from TV (RFD-TV especially). I need to be able to see how it is done in real life and not just in 2D in a book or magazine. However, I enjoy magazines because they have more specific and advanced information.