Amanuella:
... I would like to use an Electret Microphone Breakout Board ...
Would that be the SparkFun Electret Microphone Breakout?
... interested in the frequencies within the normal human audible range.
Canonically, that runs from 20 Hz to 20 kHz - a wide range. The upper portion of that range will be challenging for an Arduino, with its limited speed and memory. Conventional wisdom says that the fundamental frequencies of adult speech run from about 80 to 260 Hz, and that the interesting harmonics are below 3 kHz. Maybe you're more interested in ranges on the low end of the audible range.
FFTs ... a lot of the sketches fail to compile.
A lot of published FFT sketches require that you install a library in order to compile and run them. You can see how to install a library here. For the FFT libraries you might be interested in, the section entitled, "Manual installation," is likely to be the most useful. If you could point to sketches that didn't compile for you, we might be able to tell you whether you need a library to run them.
There are other pitfalls that you might encounter in exploring existing FFT programs. The FFT is a special case of the Digital Fourier Transform (DFT), carefully arranged for speedy calculation compared to a naive implementation of a DFT. If you're unfamiliar with the DFT, you might have difficulty interpreting your results.
A number of FFT programs expect that you have a well-behaved signal source connected to a particular analog input in a well-conceived fashion. If you run those with nothing connected to the analog input, you may well get results that are absolutely correct, but difficult to follow. I'll recommend that you use known, calculated data as input to the FFT while you're developing the FFT portion of the code, and then switch to live analog input when you have developed a level of confidence in the FFT code.
Grumpy Mike is right: there's no way that you could figure out how to connect an audio input to an analog pin on the Arduino just by looking at the code, unless you already have a fair knowledge of the Arduino's analog-to-digital-converter (ADC), and how it works. You describe yourself as a neophyte with regard to the Arduino, but we don't know anything about your experience with electronics in general. The ADC requires an input voltage that's between 0 volts and 5 volts in order to provide a meaningful reading. Many audio sources provide something like a 1 to 2 volt peak-to-peak signal, centered at 0 volts, or ground. If a signal like that is directly connected to an analog input, the reading will be zero whenever the input signal is negative. And, it can damage your Arduino. The project that Grumpy Mike references shows a method of shifting the level of an analog input to be at the middle of the ADC's range - 2.5 volts.
Having said all that, I'll note that the SparkFun Electret Microphone Breakout internally level-shifts the analog signal from the electret to 2.5 volts, and uses a rail-to-rail op amp to boost the signal. The output is Arduino-ready, and can be connected directly to an analog input. If you're not using that device, though, you'll need to either verify that it has appropriate level-shifting, or do that shifting with your own components.