It's hard to explain but here goes; have the positive wire go to one positive post, then take another wire and wire it to the previous post. then connect it to the (+)post on the other sid of the sub.
you now have a 1) a wire from you amp(+) to one of the (+)posts 2) a wire attached to the previous post and to the (+)post on the other voice coil(oposite side of the sub).
good now,
attach a wire to previous connection and run it to the other sub (+)post. good. now run attach a wire from the last (+) post to the empty (+)post.
you have now mad a chain of wires coming from your amp going to all of the positive posts on you subs. Now do the same thing for all of the positive post.