Alpine MRV-1507 Amp and 3 JL W3s

Ok, i have a Alpine 1.5 Din (857 model) head unit in my 2000 Grand Prix. I have a custom box and Amp rack that was fitted for 3 JL W3s and 2 amps, one in which is the Alpine MRV-1507 Amp. I bought this set-up off of ebay. Im trying to stick to the same set-up the previous owner had. Im not real sure how to hook these three subs to this amp. The Box is sealed and is open on the inside, meaning there are no walls between the subs! Can anyone help with this matter? Thanks ~Ed