How to cancel noise in audio signal?

Hi

I have a audio(.wav) file i want to filter, and a file with background noise i want to remove.

The files aren't the same length.

I tought if i have the frequencyspectrum of both noise and sound i could substract the noise frequencys from the sound.

But i haven't worked that often with the signal and system tools in matlab so i don't know how to do it.

Is it possible? And how?