So I've been playing around with IDLE. Then the Lesson2 tells me to open the editor window, not the shell window. I'm not sure which is Editor? I have EDLE, Python Launcher (downloaded from python.org) and TextWranger...maybe I misunderstood about sth? :'(
IDLE combines several functionalities. It contains an interactive interpreter (the window where the >>> appears in, and in which you can bring code to execution immediately), and it's a small-scale IDE (integrated development environment), which means you can load, edit and save python-files, and launch them conveniently. This functionality is meant with "Editor". Probably just go to the Menu and pick something like "New File".
Python Launcher is Editor?