What do you need help with actually. You gave no problem description. Only that you want to help your son with this project. What does not work? How does it work/what does it do, that you didn't expect?
So much for reading that code file with Notepad. It's mostly gibberish. Can't help with this. Any chance you can make pictures of this graphical programming language?
What is the resistance of that pressure sensor?
[EDIT] Never mind, nominally unpressured at 1 Megaohm according to the Sparkfun product description.
https://www.sparkfun.com/products/9376
If I look at the schematic of this Picoboard, then the analog circuit behind the jack-plug socket is the AVR chip analog input pulled up to 5 volt with a 10 k Resistor. Together this makes a 10k over 1000k resistor divider. Or the unpressured ratio that comes out of this is about 1000/1010, or 0.99 times 5 volt. In terms of ADC value this would be about 1013. Applying pressure you should see lower values. But how much is difficult to say. Have you tried to measure this with your own hand, while using a multimeter to measure the output voltage? How much does it sway. Could be that your multimeter does not measure quickly enough to register a hit of your fist. Better use weights.
