Hi,
This might seem like a standard answer, but I would read the documentation bundled with the Beekit.
1. There is a Beestack 2007 Documentation overview document that tells you what the different documents contain
2. The ZAUG (ZigBee Application Users Guide) tell you how to use the example/demo applications.
I can only recommend that you try out the step by step instructions in order to learn a bit more about ZigBee
3. then finally the BeeStack Application Developers Users guide contains step by step instructions on how to create a small simple ZigBee application.
read the documentation and try out the instructions.
If this is not enough the consider acquiring Drew Gislason's book on ZigBee - it uses BeeStack for all its examples.
BR,
Mads