sub box dimensions and volumes

I am trying to figure out the dimensions for a fourth order bandpass box for my 2 kenwood subs 12" kfc-w3009, I have my material ready to go, but i don't fully understand the box volume and port calculator, the manual for the subs provide the values for the specs, i just don't understand what they mean, I am a newbie with the tech specs. I hope to build just a square enclosure, thanks!

First, I am looking at the install sheet for that driver, and there is no bandpass recommendation. I wouldn't try it. Poor response at best (but realy... is even decent response for that woofer even POSSIBLE?), total destruction of your driver at worst. If you are bent on a bandpass I HIGHLY recommend having someone build it for you... Hardly an enclosure for a beginner. (And please don't take that as an insult - it's NOT what I mean.) Even a small deviation in either volume or port dimenions can cause HUGE variations in tuning, and as I said above, if far enough off, can completely tear your woofer apart. I recommend against the effort, as 1: it's not recommended by the manufacturer, and 2: it's a terribly difficult enclosure to build correctly.