Connect your inputs. Each vertical column on the desk (known as a channel strip) is designated for a connected input device, which may include a microphone, an instrument or a music-playback device. The jacks for each input appear along the top of the desk or along the back panel. For example, if you want to connect a guitar to channel strip 1, insert your guitar cable into the quarter-inch stereo jack on the first channel strip. You can connect as many inputs as you have available channel strips.
Connect your outputs. In addition to your input channels, you should see a series of output jacks, to which you can connect to speakers, PA systems, amplifiers and other external devices. A typical mixing desk has separate stereo and RCA jacks for the main mix and control room. The “Control Room Out” jacks are used for monitoring purposes, or for feeding output to a soundproof room or other monitoring environment. For your main output source, such as stereo speakers or a stage box, use the “Main Mix Out” or "Main Out" jacks.
Balance your inputs. The primary function of a mixing desk is to adjust multiple audio sources simultaneously in order to achieve an overall clear and fluid mix. On each channel strip, you can adjust the volume of your input by moving the “Level” slider. You can move various inputs into the left and right channels (speakers) by turning the “Pan” knob on a selected channel. Turn counterclockwise to move the sound to the left, or turn clockwise to move it right. Adjust your “EQ” knobs to isolate frequency ranges. Low frequencies (appearing at the bottom of the strip) pertain to bass sounds, while high frequencies (appearing at the top of the strip) pertain to treble, or high sounds. Use the “Gain” knobs to apply extra volume for weak-powered inputs.
Connect an external effects processor to apply effects to your mix. This will require two quarter-inch stereo cables. Connect the first cable to the “Aux-Send” jack on the desk and to the “Input” jack on the external processor. Connect the second cable to the “Aux-Return” jack on the desk and to the “Output” jack on the external processor. Use the processor menu to add echoes, tremolos, reverb, distortion, amplification and other effects to your mix.