To start working on the code itself you will need to check it out from Subversion.

if you have commit access, you cna first checkout the trunk

$svn co https://gaforflash.googlecode.com/svn/trunk gaforflash-trunk

wihtout commit access, you can still work from the trunk

$svn co http://gaforflash.googlecode.com/svn/trunk gaforflash-trunk-read-only