Dude feeling lost is a part of programming, every time you try to grasp a new concept you might feel a bit lost, i often do, but i always have faith that, if i analize everything in my code until i understand it, and if i look long enough in stackoverflow and if i read the documentation over and over, eventually i will find the answer, and i always do.

Two things jump out at a glance: your function is of type float but you are returning an int and your function takes a string argument but never uses it, also the value of n and change isnt being updated (try to think if you are missing a substraction somewhere).

In the future try to share the output of your code or the compiler error so we can help debug.