Just start. There is honestly nothing special. You won't understand everything straight away and anyone who expects to is setting themselves up for disappointment. Edit some things other people have made for your own purposes (don't bother releasing, waste of time) and see if you can work stuff out.
From there, dive in and fail, or succeed. It doesn't actually matter which. Failure will make you better to some extent and as long as you know that you are GOING to f*** up it's not such a problem when you do, remember, it's just text, if you break it, wipe out whatever you did and try again. Honestly nothing special. But you'll never know unless you start (and this is basically all i did)