please check if your Logitech Z-560 has the RCA inputs or Audio line-in functions.
likewise check if your LCD TV also have the RCA outputs or Audio line-out.
normally,you can check the availability of these connections at the back of the
subwoofer enclosure (Logitech Z-560 ) or any console that comes with the unit.
if you have those connections,then you can use the RCA cables to connect the
speakers and the LCD TV.
sometimes,both equipments can have digital audio inputs for the speakers
and digital audio outputs for the LCD TV.you can use optical fiber conection
for that.