How to use opencv 3 with opencv_contrib

Hi I am trying to use opencv_contrib code with opencv 3. I am following this instructions here https://github.com/Itseez/opencv_contrib Step 2 says to select the opencv source code folder and the folder where binaries will be built (the 2 upper forms of the interface)  Is the source code folder = sources folder ? And where is the folder where binaries will be built ? I have googled for other guides but they are all confusing as well. Help thanks