If you're willing to spend a little (and support other community members) Aaron Reed's book on Inform 7 is also very nice, and as a bonus, Sand-Dancer is available on the web for free. So you can play it, compile it if you want to, and see which part of the code does what.
Don't feel you have to understand certain parts of the documentation, as if there was a quiz on the whole IDE. You may miss parts entirely, or not understand them, until you need to make things work.