To get the latest ITK source code, you must use git. If you do not have git installed, please install it from your package manager (e.g. sudo apt-get install git). Once you have git installed, it is as easy as typing this command in a terminal window:
git clone git://itk.org/ITK.git
This will create an ITK directory and download the latest ITK source code into that directory. Step 1: Obtaining is now complete!