2 BANK CHARGER
 

I assume this is a 12 volt 2 bank charger. If so, it should have 2 cables
coming from it with a red and black wire in each cable. Select one cable and
connect the red wire of that cable to the positive pole of a battery.
Connect the black wire from the same cable to the negative post of the same
battery. Repeat with the wires from the other cable to the other battery.

Before plugging it in be sure and check the electrolyte level in the
batteries.