What model of Bose surround system do you have? Is it the Acoustimass 10?
If so, the RCA jacks on the subwoofer are for the five Bose speakers. The Acoustimass module (octopus-like plug) is supposed to connect to the speaker-out connections of an A/V receiver. The receiver has the optical-in ports that you need to plug your TV/DVD/etc into.
If you don't have a receiver, then you need to get one. The Bose system only includes the speakers.