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.
i have a brand new samsung tv with a digital audio output, my bose surround sound only has the rca connection....is there a converter for this or is my 900 dollar surround sound useless ?
Well, you can get a converter (http://tinyurl.com/4meqjmd) but it will cost you $40-50, and has a wallwart that you need to plug in. Plus it only gives you 2 channels of analog out to RCA female plugs. At least one of these says specifically it will NOT handle Dolby Digital.
You should have an AV receiver to run all this through, there are some good budget models out there from Denon, Yamaha and Sony. Denon seems to have the best upconverters if you watch a lot of non-HD content and you have an HDTV.