Ok i'm writing a program in C# using Direct3d. i need to write a spectrum analyzer in order to translate objects around the scene based on sound.

well this is where i hit a brick wall... i'm totally lost!
i've found information that points to useing a Fast Fourier Transform and i've found a few libraries that do that ( http://mathnet.opensourcedotnet.info )... but i just cant wrap my head around how to use FFT to do this and i have no idea how to impliment it. Can anyone help?