Scrolling Spectrum

[Medium]

Then what do you need? We can do marvelous things here, but reading minds ain't one. Why do so many people have such problems simply stating what they want to do, and what happens instead? Escapes me entirely.
When in doubt, post code, mark the line where compiling fails or a runtime error appears, and copy&paste the error message(s) underneath. Even if it's just that output differs from expectation, at least SOME information about what you did would be greatly appreciated. And by that I, of course, mean code.