mapserver .map file creation

Is there a fairly simple way to create a .map file from some existing
esri shape file data?

I have a working intallation, and can get a map to display but I don't
know how to create all of the class definitions in the .map file. In
fact, other than just hacking on the .map file I don't know how to
really edit it.

I've read the spec and the definitions of the attributes for .map
formats, but I haven't seen any lucid description of the process for
creating a new .map file.

I' willing to do the reading if someone can point me to some good
sources of information.

I'm using mapserver 4.4, I have the shapelibs and tools and mapscript.

Thanks in advance

Hey, try http://www.maptools.org/maplab/index.phtml which has web based
interface for creating .map files. If you're flexible about
installations, on mapserver there is a ms4w bundle that comes with
maplab (.map files), chameleon (interface tools) and mapedit
(organizing mapping web apps). They're also all available at the
maptools site and speed up the process of using mapserver.

Good luck,