Where do I connect the red/black wire onto my amp?

[lappyow]

My amp that my father gave me (McIntosh) has 4 connectors for left and right saying:
COM 4 8 16
 
So... where does the black and red go? I'm assuming the 4 8 16 = impedance, but does the red go there (e.g. on the back of the speaker, there's a black and red output)? Or does the black?
 
Also, what impedance should I connect it to? These are floor Altec speakers, that are about 5ft x 5ft x 5ft.
 
*audio noob that inherited a great sound system*
 
EDIT: How does the wiring system go:
1) CD Player/Components -> Equalizer -> Pre-Amp -> Amp -> Speakers
OR
2) CD Player/Components -> Pre-Amp -> Equalizer -> Amp -> Speakers
 
?
 
The pre-amp has no place for a speaker wire, so assuming it goes somewhere there... it has an input selector, so assuming it's setup (2), however want confirmation.

 

[wuwhere]

1. Black is common ground to all of them. So red goes to the 4, 8 or 16.
 
2. Yes, 4, 8 & 16 are the speakers' impedance.
 
3. Usually, at the back of the speakers there is a nominal impedance rating, usually 8 Ohms.
 
4. I used to have an equalizer, so CD player -> line in/aux in to your preamp -> equalizer -> amp -> speakers.