Ok so I want to learn android push notifications. I found at android to use the C2DM service.
<http://code.google.com/android/c2dm/> 

Great they even give me an example. <http://code.google.com/p/jumpnote/downloads/list>

My problem is I don't know what to do with the file after I download it. :P
It is an .apk file. So how do I open it in eclipse to learn from it?