First of all, thank you for trying GGI. The sources you obtained are the GGI-0.0.9 public release. Not all of the drivers are in working stage. However, they are included to have a broader testing base.
Please make sure you read all the README files related to the drivers, there will be useful hints and notes about what works, what is known not to work, how to fix problems etc.
To install GGI, the steps described in this document have to be done. But you will not have to do these steps manually. There are scripts (most of the time called 'configure') spread in the source tree that will help you to configure and install GGI. This document will show you what has to happen in order to install GGI to let you understand what the scripts can do for you. Read 'README.configure' for more information on the configuration scripts.
Basically you will: