If you want to try KaForkL yourself, you can just check out the svn repository for the latest version:
svn co svn://kore-nordmann.de/kaforkl
You can find a complete description of all the commands in the about document in this directory
There are some simple examples included.
The IDE to develop KaForkL programs
The interpreter (written in PHP) itself. It is completely documented, if you want to try reading the source.