Firstly, there's the wiki entry:
http://wiki.jrmediacenter.com/index.php/Stacks(or is that what you meant when you referred to the 'help section'?)
I also made a stack related post yesterday that might help...
http://yabb.jriver.com/interact/index.php?topic=46228.msg317638#msg317638Imagine you have a pile of pictures. (real, physical KodaColour prints)
The pictures are in a pile because they mostly look the same, so you piled them up and placed the best of the bunch on top of the pile so you could see it.
At any time you want, you can scatter that pile, then pile it back up again (or not, depending on your mood)
You may just decide to chuck the pile of photos in the bin and just keep the top one.
You may decide to pile them back up and place a different file on top.
MC stacks work on exactly the same premise, and can be extended to any file you like.
Play with it for a bit. Stack 'em up, knock 'em down, stack 'em up again.
The system is working really very well now.
have fun.
-marko.