To use this ATI 8MX2 8 - Channel Mic Preamp/Mixer, first connect it to the correct power supply. Then, plug in your microphones to the appropriate channels. Adjust the volume and other settings as per your requirements. When using, make sure to keep it in a dry and cool place. Avoid exposing it to direct sunlight or moisture. For maintenance, clean it regularly with a soft, dry cloth. If you encounter any problems, check the power supply first and then ensure all connections are secure.