How should I approach making an organ pedal MIDI capable?

I recently received:

  • Elegoo Mega 2560 (Which I think is exactly the same as the Arduino Mega 2560 Rev 3)
  • SparkFun MIDI Sheild
  • Detached organ 1 octave bass pedal which looks to be from a Lowrey Organ Pageant M150

I'm posting this since I don't really know where to start and need of some guidance. I have tested out the 2560 with code, making the little onboard LED flash, and attaching a small piezo speaker and making it beep. (Both unrelated to the project, but it looks like the Elegoo is every bit the same as the Arduino.)

I have a vague understanding that the shields are supposed to stack onto Unos or 2560s. I can't see how this one would stack, since the pins on the MIDI Shield don't seem to line up with the 2560. There is a tutorial, which is very vague, that demonstrates a MIDI shield being on top of a 2560: photo. If mine is a bit different and unable to stack, I am okay with that, but does this mean I can use jumpers instead?

For starters, I'd like to get the Arduino communicating with the MIDI shield. Maybe sending MIDI out to one of my synths, for instance.

The bass pedal is another story. Electronically, it looks pretty cut and dry, but I don't know if there's anything obvious to what all of the wires do (like what 14 color wires correspond to what). I'm guessing it's all the 13 keys (notes C to C), then the last wire being ground or power.

Below I have images of the pedal's wires, 2560, MIDI shield and the pedal itself. Since I'm a new user, I can only post a few links, so hopefully this bulk image link is okay. Click to see all of them: