This page is about using Cygwin with Emacs. Cygwin is a collection of tools that provide UNIX functionality on Microsoft Windows. There are two different ways Emacs and Cygwin can be combined: (1) run Cygwin shells within Emacs or (2) run Emacs within Cygwin.
/cygdrive/D/any/path/to/filethe same way you use MS Windows-style filenames
$HOMEwhen you have Cygwin installed as well as Emacs
c:\path\filein Cygwin Emacs
See CygwinShortcut for how to use Cygwin Emacs and create a Windows shortcut to it.
Other info about Emacs and Cygwin: http://www.khngai.com/emacs/