Before being able to start changing any source code, you have to get a copy of it.
The SUASecLab uses the repo tool for source code management (overlay for git to handle many repositories).
You can find more information about repo at the website of the Android developers.
To obtain a copy of the source code, run the following:
mkdir SUASecLab
cd SUASecLab
repo init -u git@github.com:SUASecLab/manifest.git -b default
You can now clone the code (or get code updates) with the following command:
repo sync