I Have A Polk Audio Sound Bar And I Would Like To Know How To Hear The Sound Fro

I had an awful time getting everything hooked up because my Polk, although new, does not have an HDMI port. So when I proceeded to connect the TV, cable box, and Blueray player all together we had to run optical from polk soundbar to cable box because ,although the TV is new too, there's no optical on the back of the LG TV. The HDMU is connected from the Blueray to the TV, which is the only way to make everything work together. Now we have the Roku with the HDMI and everywhere we've hooked it still doesn't have the sound through the polk? How in the world do I need to conect all of these things to make them all work together????