Project website: https://github.com/cyrilmottier/GreenDroid
You can find instructions how to use the GreenDroid in your projects from the project's website. In short, all you need to do is to download the project code and include it as a library project in your Android app project.
The GreenDroid creator, Cyril Mottier (@cyrilmottier), have also written about the project in his blog: Introduction to the GreenDroid library.
There's also a demo application demonstrating GreenDroid library's components (Android Market link)
GreenDroid quick actions demo:
GreenDroid action bar demo: