How can i hook up my home theater surround sound to my computer?

Right now i have a 5.1 surround sound for my home theater. Also i have my computer's sound card hooked up to my reciever through a digital optical cable. I also went in to my sound properties on my computer and it lists three things:

Speakers: not plugged in
Digital output: working
HDMI output: working

Related posts:

  1. I just bought a new TV and a surround sound home theater…what’s the best way to hook it all up?
  2. Home theater surround sound help with digital cable and ps3?
  3. hooking up home theater surround sound to cable t.v.?
  4. How to hook up Wii to a panasonic projector, panasonic home theater system, and satellite tv box??
  5. Hi I want to buy home theater surround sound speakers. If there anything that I should know?