Leitmotry is correct but I'd do it a little different. Instead of using an inline ampmeter I'd use a clip on type if you can find/borrow one. Just easier. If you do use an inline type remember...there will be a plus and minus at the inputs of the meter. The negitive side of the meter goes to or toward the neg. post of the battery or the plus side goes to the positive post on the battery.

Six volt guy living in a twelve volt world