Reply to Need Help with Equipment Please!!

Need some help setting up my gear .
Hi this is my first time here and my first post.

Anyway, I was minding my own business when a friend got sick and had to sell his brand new DJ gear . He was buying gear a little at a time until he had everything but then got sick and had to sell. I thought well I've been looking for something else to do, so why not. Unfortunately he moved out of state and is no condition to give me advice anymore.
Here is what I bought. All brand new with a few hours of playing time just to see it work.

Denon X1500s mixer
Nutech DDS80 with an upgraded 500 gig drive.
1- set B-52 matrix 2000 speaker system
2- Peavey SP4 speakers
1- BBE ds26 crossover
1- Behringer EP4000 Amp
Chauvet Obey 40
Also a brand new home built quad core PC box made for Karaoke with the CompuHost software. Dual video card.
VovoPro receiver for 4 wireless mics and the mics.
1- 8X10 DJ Projector screen with the truss sysytem from djscreen
1- Vivetek D330WX
Dell Inpsiron all in one Pc system for the CompuHost software. For independent sign up of singers and songs.

OK, well I really don't know that much about this stuff and need some feedback on how certain things work.
For instance. He had the 2 lines coming from the mixer to the 2 in 6 out BBE crossover. then 2 came out of the BBE to the amp and then to the SP4's. The other two lines coming from the BBE went directly to the Matrix Sub and from there to the other 2 smaller B-52 speakers.
Well that seems to work pretty good. It's very loud and sounds pretty good to me.
The thing is that I want to add an SP218 dual sub woofer and I guess it would also need another Ep4000 for power.
The problem I am having is with the BBE. I don't understand how you get so many cables from speakers to only 2 lines from the mixer.
I have been trying to understand the BBE and from what it looks like you can't have 6 speakers coming out working correctly with each other. Do I need something different? Is there a better way to do it? Please don't tell me well you should have gotten a whatever.
I have what I have to work with and that's the bottom line. I just need to make the best of it however I can.
I don't know enough but I was seeing that the speakers have pass through . Is that something that I can take advantage of without having to buy anything new? I was believeing if that works I could run the matrix speakers through the SP4's. I don't know, that's why I am here guys. What you help me with.
Any help is very much appreciated.