Okay kiddo, let's talk about Peter Westergaard's tonal theory. Basically, it's a way to understand and analyze music. Just like how you have rules when you're playing a game, there are rules that go along with making music.
One of the big rules in music is called tonality. That's a fancy way of saying that each piece of music has a certain "home base" note that it keeps coming back to. Kind of like how you might always come back to your house after playing outside.
But there's more to it than just that. There are also certain chords and melodies (that's just a fancy word for the tune) that sound good together and create a certain mood or feeling. And Westergaard's tonal theory is all about figuring out how those chords and melodies work together.
Another thing you should know is that music is often divided into sections, or what we call "phrases." Each phrase usually has its own little melody and chords that go with it. And those phrases can be grouped together in bigger sections, just like how you might group several toys together to make a bigger toy castle.
So when someone is analyzing a piece of music using Westergaard's tonal theory, they're looking at things like how the different phrases and sections fit together and why certain chords and melodies sound good together. It's all about understanding the "rules" that make music sound good.
And that's the very basic explanation of Peter Westergaard's tonal theory, kiddo!