No need to get component cables. Page 20 of the manual. The set should have come with a special cable. Plug your red and white (audio) into the red and white on the special cable and then the yellow into the green (video) of the special cable. Then plug into the back of the ST50.
Klipsch RF-52 II // RC-52 II // RS-42 II
Klipsch KG 2.5