PIR Sensor Cant get to work

Hi All
So i bought a pir sensor from radio shack about a month ago and i have not bean able to get it to work. Its the one by parallax http://www.parallax.com/dl/docs/prod/audiovis/pirsensor-v1.2.pdf So i was wondering if some one could help me with it. THANKS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!