Step zero should be to see if you actually enjoy software development. It would suck to switch careers and find out that it's not a good fit for you.

I would suggest starting with Processing. It's a very simple programming language with very easy-to-use tools which was made specifically for learning by non-programmers. Just go through the video tutorials at https://hello.processing.org/ or at Khan Academy.

You may never use Processing again, but the concepts will carry over and it will give you a feel for what learning to program is like.