That link has a ton of example programs. Even has examples for using timers and controlling 7 segment displays etc. You just have to read through the PDF files.
The pseudocode richiereynolds posted above is actually REALLY useful. Figure out how to do each of the lines individually, the put them together to get a working program.
I'd first start with "how do I receive input from a microphone to a PIC microcontroller?" then "how do I determine what the frequency of the input is?"
Once you can answer those two questions, you'll be very close to being done.
Also, I honestly don't think posting a bunch of code will help you much. A, you won't be able to copy it, B, you probably won't understand it, and C, it won't have anything to do with your project whatsoever.
I know when I first started I'd look at code and just get frustrated because I didn't understand what anything meant.