Gary, If you have the LG Blu-Ray player there is an "optical" button on the remote. Press this to play the tv through the stereo. There is an optical wire that needs to be connected between the tv and stera as well but that should have been done at the factory. Mine came unplugged from the tv when the satellite installers were connecting the HDMI cable. I didn't discover it until I wanted to use the stereo for watching tv.
If you have a different brand blu-ray player it probably has a similar feature but may be named differently. I'm sure someone else here has experience in the matter and will post a comment.