Question on the driving template

Hi all, basic question, but I did do a quick search and couldn't find anything like this asked before.

I am learning the engine, and am trying to understand how to make a car that drives. I used the driving template, but I am not sure how this works. I am familiar with some of the basics, and found the IMC and IAs in the Input folder, as well as the "VehicleAdvPawn" blueprint, which looks like where all of the magic happens.

The problem is, it's a black box to me - I see the chaos Wheeled variable, but don't know how the data flows. I would like to see the full line between "player presses button" and "increase this variable".

If anyone could help, even if it's pointing me to where I can learn this stuff without bothering everyone, I would be very appreciative! Thanks in advance!