Set up your Peavey mixer on a flat surface in a location in front of and facing the speakers. This will allow you to gauge the volume of sound and adjust accordingly. Connect the power supply to your mixer.
Connect an XLR cable to the microphone and run the cable to the mixer. Connect the cable to the "Mic" port of an open channel on the mixer. Repeat this step until all of your microphones have been connected.
Connect one end of a balanced cable to each of the jacks labeled "Outputs" on the Peavey mixer. One jack is the signal for the right-side speaker. The other is the signal for the left.
Connect the free ends of the balanced cables to the corresponding left and right inputs on your powered amplifier. Make sure your amplifier is connected properly to the speakers.
Power on your mixer and amplifier. Have someone speak into the microphone while you adjust its level from the mixing board. Adjust the levels for each microphone you are using to achieve a good mix. If you experience feedback from a microphone you can try to reposition it in relation to the speakers, or you can use the "EQ" knobs on the Peavey mixer to cut out troublesome frequencies.