Manual Here

7) Attach your speaker wires to the speaker, being sure to observe proper polarity
(amplifier speaker output positive (+) to the red terminal, amplifier speaker
output negative (-) to the black terminal).
8) Holding the speaker carefully above the bracket, lower it slowly until the bracket
is fully inserted into the groove on the back of the cabinet.
VERTICAL MOUNTING
After completing all connections, turn the system on, then GRADUALLY increase the
volume level. If there is no sound, distorted sound, or if the amplifier shuts itself
down after a few seconds, IMMEDIATELY TURN THE VOLUME DOWN and turn the
system off. Then re-check your wiring for accuracy and for possible shorts at the
connecting terminals (adjacent bare wires touching each other). When everything
sounds fine, keep the volume reasonably low while you familiarize yourself with your
system's various controls and operating modes.
HORIZONTAL MOUNTING