Hertz? No, not the car rental.
 

I'v searched and sought and looked and searched some more, and I can't find an explination of hertz. I need a general idea of how to recognize an instrument or sound's frequencies to use an equalizer. Can anyone help? I know I sound dumb, but that's because I can't find information online so as not to. Thanks!

hertz is a measure of frequency, and it doesn't only pertain to sound, for example your computer's processor is measured in megahertz meaning how many thousands of calculations per second it can perform, aka the frequency of calculations.

Hertz
Sound frequency

I did a Physics project on sound, very important field. I miced a range of instruments and performed differrent notes, octaves, thirds, fifths, fith chords, octave chords, etc. Then placed these recordings into CoolEdit, and gathered the graphical information. It was great fun, finally something in Physics that I really really enjoyed. Screw Newton's Laws... I love sound. :D

Sorry kind of off-topic...
I learnt so much on Fourier Analysis/Transform through that project, I'd recommend giving that a go on Wikipedia & books, etc.

Overall in definition Hertz (Htz) is the number of cycles per second. So by definition if I clapped my hands 5 times a second I could claim that as 5 Htz, just as a crude example.
The note Middle A on the piano is 440 Htz, therefore the number of times that the piano strings are resonating (Or vibrating) at is 440 times per second. The same applies for Middle C (261.6 Htz). This only applies when calculated in equal temprement Different instruments have different properties as to their waveform, which initially will make them sound different.

Links:
Overtone
Audio signal processing - refer to equalization link
Harmonics
Fourier Transform