Just go from the "subwoofer out" to one of the "low level inputs". Turn the frequency selector on the sub all the way up.
Then you have to go into the receiver settings, set your speaker sizes to "small", subwoofer to "yes". Crossover setting on the receiver depends on the size of your speakers, try 80hz with larger ones with 5.25"+ drivers, 100/120/150 with smaller satellites. Run auto-calibration w/ microphone if available on your receiver, else use the test tone and a sound meter to set the volume, or do it by ear.
