Ok, the title says alot

Anyway, I have started with this tutorial from the Ruby Resources thread. I have even made it to the "learn to program" page and run the calc.rb program and it worked, but there is some confusion on my part. As I say I am not a programmer. I figure I better ask so I can actually learn something or quit now if I am too stupid

What does this mean in layman's terms?
To get to your command line, select Command Prompt from the Accessories folder in your start menu. You will want to navigate to the folder where you are keeping your programs. Typing cd .. will take you up one folder, and cd foldername would put you inside the folder named foldername. To see all of the folders in your current folder, type dir /ad.
Like I say, I opened the Comand Prompt and ran the calc.rb and I got the 3 so I must have done something right. Now if I could understand what the Command Prompt window is and what it does maybe I can move to the next step.

Sorry for such a newb question, but we all have to start somewhere.