If your subwoofer doesn't plug into the wall outlet it is passive and needs to be connected to the left and right front speaker terminals. If it has speaker out connections as well as in then you connect the front speakers here. If not then the sub connects along with the front speakers to the front speaker outs of your system. Make sure you get the + and - connected as marked.
n the set up menu set the front speakers to large and the sub to none. This sends the bass to the front speaker outputs that the sub is connected to.