gv, X problem, or pilot error? How to do?

[LDR]

If I try to execute 'gv' from a Cygwin bash character cell window, e.g.:

    $ gv /usr/share/doc/clamav/clamav-mirror-howto.pdf

I get:

    gv: Unable to open the display.

I figure (knowing little about X windows) that I must execute from an 
xterm ('xwin'), so I do:

    $ gv /usr/share/doc/clamav/clamav-mirror-howto.pdf

and, I get a Ghostscript message box:

    Unknown device: x11

Trying to read in (open) the file from a bare 'gv' command does no better

How do I view a pdf file from a command line?

A clue, please! Someone give me a ghost (so to speak) of a chance!

cluelessLee :-[