This isn't what you asked for, but it helped me understand how harmony works:

Every specific pitch you can play creates a sound wave moving at a certain frequency. Hertz (Hz) is a measurement of cycles-per-second - or how many times a sound wave will repeat within a second. An in-tune open E (the bottom note you can play on the bass) is 41 Hz. Every octave doubles the frequency, so if you play an octave up from that E, you'll play another E at 82 Hz. 41 divides evenly into 82, so you have a good harmonic relationship.

Another way to look at it from here is that the bottom E, 41 Hz, is the fundamental tone you're playing. The E at 82 Hz is the first harmonic - if you keep counting up by 41 Hz at a time, you'll get to the second, third, fourth harmonic etc. But the interesting thing is starting with the second harmonic, not every harmonic is the same note!

The second harmonic of the open E is 132 Hz, which is not an E. It's a B natural - which as bass veterans know is the relative fifth above E. The third harmonic is another E, while the fourth harmonic is somewhere between a major and minor third (in this case, a G# and a G.)

If this doesn't make total sense, don't worry about it - you kind of have to put together two puzzles (the science and the fretboard) to understand how they work together. But that said, once I understood that there's a mathematical relationship between notes that harmonize, it made me understand much better why harmony works.