Composing, if you ask a music student, is the process of taking a musical idea and exploring it. A series of explorations are expanded, revised, tweaked, and trashed until they’re organized into some kind of final form.
Mozart’s String Quartet in Bb Major, K. 458, for example, starts with a pretty little melody that includes the note F as a grace note, a flourish, and eventually, a trill. Mozart then expands, transforms and develops that trill into about 30 more minutes of themes and melodies.
Grace note, flourish, and trill.
If you’re not familiar with it, check out the first movement and hear that trilling repetition echo throughout the entire piece.
For the parade, we definitely have a theme to work with.
Dun duh-duh dun dun, dun duh-duh-duh-duh-duh-duh…
Breaking it down into its raw materials, we have a chord progression, a melody, a bassline, a rhythm, two styles (Baroque & Hoedown), and all of the tropes that each of those styles implies. For example, baroque music tends to have lots of little frills and running notes as you can see in the 8th note phrases above. All of J.S. Bach’s output was in the Baroque period, if that helps.
So if we de-baroque the melody, we get something like this: 
Which, when translated to the EDM language of 808/909/303 becomes:
See how that works?