You use a common insert cable. The TRS goes into a channel insert jack and the TS go into the in and out of the compressor. The Behringer's manual should tell you which TS is send and which is return. The send goes into the input of the compressor and the return goes into the output.

It's entirely possible the compressor needs the full 16V to operate.

a few questoins

hey thanks so much for helping me!I did some reading and i wish i didnt have to ask you this question.But I am confused about the trs and the ts.If you mean tip-sleeved or whatever then do you mean 1/4inch cables,like guitar cables and if it did need the 16vac would it turn on like it does with the 12?Thanks so much.
Unfortunately I dont have the manual anymore for the mixer

The adapter will be TRS> tip/ring/sleeve to two (2) TS. tip/sleeve. the one marked goes into the input of the device and the one marked goes into the output.

If your wall wart was 16 volts then you will need at least that much to operate the device and you must be cognizant of the phase of the power in order not to short out the power internally. Also be sure that your wall wart power is the proper voltage as far as ac/dc. This will also take out things internally if improperly applied.A 12 volt adater is probably enough to light the lights and the power supply indicater but not enough to process signal. You can go online to both of the companies you have gear for and get all the specs necessary including the power supply's part number as well as download an owners manual for both.

Perhaps this time you will keep them on file for the future. I own a cheap file cabinet full of owners manuals, warranties , as well as instruction books. I dont NEED them personally but I have them in case I sell an item. It goes well with the original packaging and shipping cartons.

To refine Dave's power supply info, you want to match the voltage, polarity and connector type exactly, and meet or exceed the current requirements.