Lestat, we all have to start somewhere* and there is no shame in creating a new thread about how to get started with Ruby and running the command prompt with it.
I'm not a huge fan of LCTHW, though I'd recommend it way above Codecademy any day of the week. I post it for you because he describes exactly how to set up Ruby in all the OS's:
http://ruby.learncodethehardway.org/book/. He suggests using Notepad++, gedit, or Text Wrangler. He warns against advice using emacs or vim, and he is absolutely right here. I'd definitely steer away from an IDE for right now as well.
*Recall we all came here as poker morons and I just started programming 2 1/2 years ago. This forum is an amazing resource and there are posters of all levels here. No one will get mad at you for starting out.