Is very simple, then is not.
Ideally anything you want to play on SB needs to be hooked up DIRECTLY to it, this way: SOURCE --> sb --> TV. The SB then needs to have multiple audio inputs.
if the audio source is hooked up directly to the TV for whatever reason then you have to rely on 2 methods:
1. TV (hdmi) ARC --> SB (both pieces must support ARC, consult manual if necessary.
2. TV (toslink) ---> SB. Here obviously you need TV to have a Toslink-Out, and your SB a Toslink-In.