Hmm, with one exception(or assumption might be a better term), my explanation couldn't be any more basic. The only thing I left unsaid was the definition and perhaps application of the half step. BTW, it is the closest interval between two notes in Western music. Probably the best way to make it tangible is by looking at a piano keyboard: Every note is one half step apart.
The relationships between pitches and between intervals is intricate and interdependent, which is exactly why music theory is such a difficult class. There is no more rudimentary breakdown of how it all works than what I posted previously, i.e., if you think my explanation's complex, take a gander at my Theory textbook.
Let's face it, written down Western music is utterly foreign in form to any other form of written communication(which is what it is, make no mistake). Hence, it is baffling to the uninitiated. It's far easier to learn to read music than it is to understand why and how it's put together. When I composed the explanation I wrote, I thought I was acutely aware of my audience, and worked very hard to avoid attempting to flaunt a bunch of flowery terminology, or talk down to my audience.
Think of it as more of assembling a Chinese puzzle than building a brick wall.
uch: