Welcome to the forum!
You should be able to find this information in the manuals for your TV and sound system.
Just to give you an idea of what's involved, you'll probably be using a
Toslink cable to connect the
S/PDIF port on the back of your TV to the same port on the back of your sound system.
If you still don't have sound, some TV's have a toggle in the options menu that enables the audio output. (It's manual will help you know what to look for.)
The sound system likely has multiple inputs, that can be cycled through, so you'll want to make sure the right one is selected. (Again, the manual will help you know what to look for)
Also the obvious, make sure your speakers are attached, and the volume is up.
Best of luck!
Cheers,
Chris