Familiarize yourself with the location of the equalizer. An equalizer usually has a series of vertical sliding controls indicating control over the labeled frequencies. Some equalizers are controlled digitally or using software equalizers.
Play with the equalizer sliders while listening to a familiar song to get acquainted with the levels' effect on the sound. The sliders (sometimes called "faders") are the vertical sliding controls that adjust the equalizer levels on your sound device. Move each slider up and down individually to hear how the sound changes with each slider.
Understand the meanings of the numbers listed on the equalizer sliders. The numbers on the equalizer correspond to the sound frequency controlled by that equalizer. The frequency on the sliders is indicated by Hertz (Hz) and kiloHertz (kHz). One kHz is equivalent to 1000 Hz, so the bass tones, 250 Hz and below, are at a lower frequency than 10 kHz, a high-pitched tone usually found in the sound of cymbals.
Set all of the slider levels at the center. The center of an equalizer slider is the zero level and will produce levels roughly similar to those set in the original recording.
Play the media with the sound levels you wish to adjust. Listen to the sound for a moment and determine which tones needs to be boosted and which need to be dampened. If the sound is tinny and hurts your ears, chances are the high frequencies are too high. If the sound is muddy and vocals are difficult to hear, the middle or high tones may need a boost. Move a slider up from the middle and the equalizer will boost that sound frequency. Move the slider below the middle and the chosen sound frequency will be dampened, lowering the frequency levels in the original recording.