You open some file, you change something you have no idea what. And let BC blow up in your face.
Do this a couple of times, and suddenly you get pointed to this console thingy. Now combine that with some insight into programming, and learning the fact that BC is backed by Python, combine learning C++ with Python and you get a pretty good basis. Atleast it did for me, but I seem to have some "natural" talent in this business. But this was some time ago, and now I've learned a couple of other languages as well, which makes me an even more competent programmer.
One thing can't hurt (much), read and try. The console is your friend, it provides feedback directly on what you do, even better, this means that you can do everything that you can put on a single Python line! Which pretty much contains everything you need to do. One exception, you can't put do things that cross multiple blocks (such as if statements).
Think of it as one big, dynamic, function, and Python dutifully waits for you to enter the next line.