How to connect subwoofer?

I have two FBT Maxx 4a's connected to a Behringer Xenyx 1222FX mixer, and the mixer is connected to a computer. Now I decided to purchase a new FBT ProMaxx 15Sa subwoofer to get more lows into the music.

But I'm a rookie at this stuff so I don't know where I should connect the subwoofer.

Here is a picture from FBT Maxx 4a's back panel:

http://catalogs.infocommiq.com/avcat/images/products/gallery/large/FBTMaxX4a_control panel photo.jpg

FBT ProMaxx 15Sa back panel:

http://fbt.it/ENG/PAE/PRODOTTI/SPEAKERS/ProMaxX/ProMaxX-15/zoom-15-rear.jpg

And the mixer:

http://img404.imageshack.us/img404/8991/x1222large.jpg

Any help would be greatly appreciated. Thanks!

(I know the mixer in the picture is 1222USB but it is nearly identical to my 1222FX.)

 

If your not using the internal fx,and they can be turned off id use that output from the desk,and dial in the amount of sub you want using the fx control on the indavidual channel strip,you could use the mon output,but there pre fader so the level wont change in relationship to the fader position

 

Thanks for the reply.

No, I'm not using the mixer's FX or anything. What exactly do you mean by "output from the desk"? The "main out" in the mixer?

And by "mon output" do you mean monitor output (i.e. Maxx 4a's XLR out)? I gave some thought to that, that by somehow "linking" these 3 speakers it'll work, but I just need to know exactly what cord goes where.

 

sorry i ment the FX and monitor sends on the desk,that way you can adjust the level of the sub without affecting the main signal output,if you use the monitor output on the desk the indavidual faders wont have any affext on the sub mix,were as if you use the fx send ,adjusting the channel fader will also adjust the level going to the sub mix

 

Do I need to buy a cord like this?

http://www.tvcables.co.uk/images/items/1m-xlr-to-jack-mono-ts.jpg

Because there is only XLR in/out in the back of 15Sa, but in the mixer there are not many XLR outs.