How to use sparse to check my driver

I am trying to use sparse to check my driver that I developed.

From http://kernelnewbies.org/Sparse, It said 'make C=2 drivers/staging/wlan-ng/', what does it check it I do 'make C=2' and how does it actually call 'spare'? Do I need to modify my Makefile to add a new target or something?

Thank you.