The command to start xmh looks something like this:
% xmh -display foobar:0.0 -geometry 660x460+200+5 &
That command opens a 660x460-pixel xmh window close to the
top of the 0 display on screen 0 of the
host foobar. If you have both monochrome and color
screens, the monochrome screen may give you a faster response.
The -geometry setting makes a different xmh window
size than the default. If you want the default size, leave out
the 660x460 in that command line. If you want the window
in a different place, change the +200+5. Your window
manager probably lets you place the window yourself -- in that
case, you can omit the position completely. The Sections
Command-line Options and
Changing How Commands Work list other
xmh command-line options and explain how to store your
favorite geometry settings as defaults.
To start xmh now, you can type the command line in an xterm window. If you want an xmh window to open automatically whenever you start X, add that line to your startup file (like .xsession). If your window manager has a menu and xmh isn't on the menu, you might add it.