Few extensions example can be found here. I suggest to analyze few extensions there and you will get an idea how all works.
If you want to activate extension you have to edit
and change the following part to
'extensions' => array ( 0 => 'customstatus' )
In this exmaple we are activating customstatus extension. Make sure you disable cache while developing.
Just take a look at this file
In this class you can define to what events your extension should listen.
Just execute this search on github and you will know
Here is example to what events Automated hosting extension is listening
Developing application takes a lot of time. You can support application by donating. There is no company behind this application and it takes away my free time. Every donation matters and does not matter how small it is!