Parametric EQ Help

I bought that Alpine CDA-9835 and I'm using the i-personalize website and I've got the x-overs pretty much figured out and I just did some rough measurements to get the distances to the speakers/subs for the time correction and everything but I'm having problems with the 5 band EQ

so can anybody give me a rundown on what will happen dependin on what I change?

ie..if I change the width, what will happen to the sound at that particular frequency it's at?

if I change the frequency that it's at what will happen.

and what will happen if I change the db(+ or -)

and what frequency range should I have all 5 bands in? ie..I know that the human ear can't hear past 20hz so no point in worrying about any settings there, but how high would I set the last one and how far apart from each other? and is it okay to have some flat sections in there or should it be flowing?

I'm a noob to audio/car audio and I figure if I wanna start learning I should get some good equipment to learn from...hehe

if I can tune mine properly, to hone my "skills", my friend has asked me to help tune his alpine too.

I know I know...tune it to how I like it and all...and I plan to. but with me, if I don't know what's changing and I'll have a hard time tuning it properly.

thanks in advance to all and any who help...

For the width, it ranges from 1-3. 1 being the narrowest, 3 being the widest. Below is a graph out of a Pioneer manual that shows how the EQ width affects the response curve (1 on Alpine = 2N on Pioneer, 3 on Alpine = 2W on Pioneer). As you may see, a wider curve will produce a smoother response curve whereas the narrower curve will boost/cut mostly the center frequency. If you don't use any boost/cut, this setting will do absolutely nothing. If you set boost/cut to +1 or -1, I doubt you'll notice a difference. You probably won't notice a difference until at least +3 or -3.

If you look at the graph below, the center frequency is the point, well, right in the center. It's the point that is boosted/cut the most. If you don't use any boost/cut, this setting will also do nothing.

The dB setting boosts/cuts the center frequency and, to a lesser extent, the frequencies near the center frequency (depending on width). If you set the dB setting to -2 @ 80 Hz, it will reduce output @ 80 Hz by 2 dB.

For the bands, I would would go with every second octave ... An octave is a doubling or halving of a frequency.

20
-40
80
-160
320
-640
1280
-2560
5120
-10240
20480

So I (personal preference) would start out with 40 Hz (Bass), 160 Hz (Midbass), 640 Hz (Midrange), 2,560 Hz (Low Treble/Voices), 10,240 Hz (Treble). I'm not sure if you have those exact settings on your HU, but I would set them as close to those frequencies as I could. Again, that's just what I would do.

You should have one band in each of the following : Bass (20-80 Hz), Midbass (80-320 Hz), Midrange (320-1280 Hz), Low Treble/Voices (1280-5120 Hz), Treble (5120-20480 Hz)