Getting extend information from GeoTIFF

[Dennis Megarry]

I am a complete newbie to mapserver and am switching over to it from years
of using AspMap.  My main purpose for moving is that AspMap does not
support GIF w/World files.

I want to use the GIF files as layers over a GeoTIFF.  What I can not
figure out is how to get the extend info from the GeoTIFF or GIF file to
build the MAP file.  Is there any "HOWTO" documents on this subject? or a
GUI created to help develop your MAP file?

Any help would be extremely appriciated..

Dennis