1.) When you type a command, you are running a program. The program(s) are not "command prompt". You can run any program from the command line.
2.) The Windows command shell scripting facilities are _terrible_, making it almost pointless to use.
In a sane CLI (like the Bourne Again SHell, bash), there are ample facilities for programming interactions between programs, and even writing most with just the facilities built in. Windows' CLI has none of this and is the worst "programming language" I've ever had the misfortune to use.
The point of a CLI is that it's easy to automate stuff. In Windows, it's almost impossible to automate anything.
I have only toy experience with the new "Powershell". I do know that it exposes the seemingly overcomplicated .NET runtime, and that's about it.
I strongly recommend that you install either Cygwin or MSYS (depending on your needs), which both include Windows ports of the (Unix) Bourne shell and BASH, among others. Using these instead of cmd.exe would be much more useful and more productive.
I'm assuming you already know how to bring up a command prompt box.
Go there and enter "help" (without the quotes).
This will bring up a list of 88 commands in alphabetical order.
Scroll up and see the first command is "assoc".
So, type "assoc /?"
This will display help on that command.
So, the way to learn is as follow:
Decide something you want to do. Browse the list of command for one or more that sounds like it might do what you want to do.
Then look at the help screen for that particular command.
You can also do a google search by entering
DOS assoc
(assuming you are starting with the "assoc" command).
