[CMake] Total cmake newbie needs some help

[Edgar]

I'm trying to help my friend get OpenLayer 2.1 to build and I'm having 
some problems finding certain packages during the cmake call, and some 
linking problems during the build process.

So, my first question is, what is a typical setup for finding a required 
library dependency? There are several generated files named things like 
FindALLEGRO.cmake, and FindFREETYPE.cmake, how do I generate those 
files? I need to find both zlib and libpng in order to build the demo 
programs.

My second questions is, how are link libraries set in the cmake build files?

Please be patient with me, I am a total newcomer to cmake, and my friend 
really needs help with this to upgrade his MinGW, Allegro, and OpenLayer 
versions....

Thanks,
Edgar