Just take it one step at a time and "develop" your project.
I see 3 basic things you need to do -
- Design and build LED output.
- Design & build the audio input.
- Write the program (sketch) for the various LED patterns.
For the LEDs, I'd recommend starting by adding a few LEDs directly (with a current limiting resistor) to several of the Arduino outputs, and then experiment with modifying the [u]Blink LED Example[/u] to make the other LEDs blink, and make some patterns, etc... Just to get the hang of it.
You'll also want to experiemt with the Blink Without Delay example, because you probably don't want your final program sitting there, doing nothing, waiting for the delays to expire.
Next, you'll need to do some research and make a decision about using a matrix, or another method, in order to drive the number of LEDs you want to use. That's likely to be the hardest part of the project. You might want to skip that for now, and just use 6-or-7 LEDs on 6-or-7 Arduino outputs.
I'm working on a project now that has 48 individually-addressable LEDs running off six 8-output [u]Maxim[/u] LED driver chips. With the serial input, I only need to use 3 output lines from the Arduino. In my application the LEDs are a few feet away, and it made sense to minimize the mumber of wires in the cable.
And, you'll need to experiment and learn how to turn on & off one LED at a time with whatever matrix or serial shift-register design you've chosen.
The audio input will need some external curcuitry too (probably an op-amp). Again, you can do some research and make a desision. I use a [u]Peak Detector Circuit[/u] and with a resistor and a couple of diodes to keep the voltage in the 0 to +5V range for the Arduino.
If you you want the lights to respond to different frequencies (pitch) there is a handy-dandy chip for getting 7 frequency-band oututs for 7 Arduino analog inputs. (I wouldn't try frequency-filtering in software with the Arduino.)
Once you get your hardware working, then you can play around with the fun stuff... Manking the lEDs blink interesting patterns with the music!
I don't want to be too hard on a new guy, but your "casual" writing style (using made-up words like "wutever" and "wut", etc.) won't cut it when you start writing software! ;) You have to be very precise, and it takes a precise attitude... If there are any little errors, you'll have a bug. And, there will be errors... Professional programmers make errors every day!
So, when you start writing code (writing your sketch), write (or change) one or two lines of code at a time, and test what you've done before continuing. If you try to write your whole sketch in one shot, you will have lots of errors and you may not be able to find & fix them. Pro programmers do this too... They write and test their code a little at a time (but maybe more than one or two lines).