what OS are you using? WindowsXP or earlier?
The files should just be able to be copied to disk without opening them. This can of course be done in Windows.
Are you asking what DOS is? If so then DOS is an old operating system that has been banished from Windows XP. You can still however, use DOS programs in an emulation mode from XP.
Bascially it's Command Line Interface (CLI) interface, not a Graphical User Interface (GUI) like Windows. Everything is controlled using commands.
Here's some links that tell you about DOS commands.