So it is a mono amplifier, but I still don't understand how to hook up one subwoofer to the amp.

Do I bridge the two outside speaker, 1 + and 1 -, together? And if I do bridge it, is that what rms rating they gave the amp? (400w at 2ohm)

Link
http://www.rockfordfosgate.com/(S(3x31eawe2q5fi4m5hulyksck))/products/product_details.aspx?itemid=116170
Picture:
http://www.rockfordfosgate.com/images/products/P400-1/P400-1_3_l.jpg

Thanks