Understandig boxes and the tuning calculator help

[G-Rad]

My buggest weak point in car audio is box designing and tuning understanding. I can build them all day long.

I dowloaded the Box Tuner Calculator in ordr to play wit i and hopefuly learn it, but honestly, I' lost within the calculator it's self. What I tried to do was map out my initial idea for a simple box for 2 12's with dual cetered slot ports. The ports/speakers will be divided down the center ofthe box. If I coul get some assistance mapping that out into the calculator and knowing how deep (I believe leaving a .75-2" gap between the back wall and the inner-port wall, that separates it from the actual driver

I'm sorry for confusion, but if I can figure out how to map this out into the calculator, it'd help me understand it more. (I know I have an ass-backwards way of learning things.

Thanks in advance.

If it elps, the box design idea, for now, is a 2 12 setup. Right now I got a single 12 in an 18x15x13 box (WxDxH)