Click on the DOS icon in the Main program group, and a window pops up on your screen that looks just like what you see when you start up your computer, but don't load Windows. Or you can pull down the Run item in the Program Manager and get a little box that lets you type in some, but not all, commands that you would type at a DOS prompt. It's mostly a matter of convenience. Keeping Windows around while you run DOS, however, extracts a performance and memory penalty, which is why you have to run some programs, including games, directly from the DOS prompt after you exit Windows. Duplicate ways to get at DOS aren't the only sources of confusion, though.
Editors are too.
Editors, aka word processors, are scattered around Windows. Typicially, you'll get a word processor as part of a Works package, or maybe your particular bundle will include a more powerful stand-alone program like Microsoft Word. But these mini-programs have their uses nonetheless. Lots of people, me included, also use Notepad when they mess with autoexec.bat and other text-based configuration files. It is sometimes installed as an icon in Windows too, where you really don't need it at all.