How to add more speakers?

Hi Everyone

I have a Denon D-M71DVS which comes with 2 small speakers and a subwoofer.

Moved into a new house which has a family room with 4 built-in wall speakers (2 are base)and would like to use those instead.

Problem is the Denon system only has 2 sets of connection terminals - ie 2 red (+) and 2 black (-) -

I've hooked up 2 wall speakers but don't know how I can hook up the 2 base speakers. The subwoofer was plugged in via a jack type of outlet whereas these base speakers have copper wires like the other 2 speakers.

Help!

Thanks!
Esther