The included story can give you a 'barebones' on how things work in Renpy coding wise.
There are also a few widgets out there that can help you with the proper spacing of nested code and such. I've used SCITE before, but I'm seeing something about an integrated text editor in my google search just now, no idea what that's about. I'm still old skool though, and mostly use Notepad2 for most of my Renpy editing on those rare occasions that I feel the need to mod a game or something.
If you want to try more elaborate stuff, the Lemmasoft forums cover a lot of topics. Google is your friend here! Just be ready for 'complicated stereo instructions' kinda documentation. Examples of code in actual use can be challenging to find sometimes...
You can also look at existing code, say DMD, for ideas if you don't mind wading into a wall of code.
unren.bat, available elsewhere on this forum, can often extract pictures and code from .rpa files, so that you can work with them. I mostly use unren.bat so that I can just look at the pretty pictures though, without having to play the game...