Connect the positive + red charger cable to the positive + red battery post. Then connect the negative - black charger cable to the engine somewhere. Most engines have something metal sticking up...
In order to understand how a battery charger charges a battery, let's touch on some basics and then crush the question with an answer. A battery is basically a storage device that stores electrical...
what kind of batteries do you have?? if the mobile phone's battery, just put in your phone. If it's car battery, just connect the red cable to positive, black cable to negative plates.
the red wire goes to the positive + side of the battery the black wire to the negative - side of the battery if the battery has caps on the top loosen or remove them while charging