I assumed since you're both 15 (according to your profiles), you were both still in high school.
Well, it doesn't necessarily have to be written down on paper (although that would be a good idea). You could have it all typed up in a Word document. It just needs to be recorded somehow.
Psuedocode is where you write out sections of your code mostly in English, to make sure you know exactly what you want before you actually write it. It doesn't use any of the programming syntax, which means you can easily transfer it to any language. For example:
if playerExperience >= requiredExperience
set levelUpPoints to 3
show levelUpScreen
set requiredExperience to requiredExperience + 100
end if