First, don't worry about PowerShell. You don't need it. There are better tools to use for the same purpose. Even if you do end up using PS via a terminal package, just treat it like any other command line.
In this world, there are code editors and then there are integrated development environments (IDEs). An IDE is a code editor with a bunch of additional features packed in, and they're all designed to work together (that's the "integrated" part). Atom is a code editor that happens to be flexible enough that users can build it into something that resembles an IDE. Atom has multiple packages that can be used to run Python code, including
hydrogen, but all of them rely on external executable files to make them work.
The first thing you need to do is figure out whether you need Python 2 or Python 3 for the tutorials, then download that version. The second thing you need to do is figure out what you want to use to write code. I love Atom, but it doesn't hold your hand at all. In my mind, that's a good thing, but if you're looking for a curated, easy experience, you want to choose an IDE like IDLE or PyCharm Community.