How do I interface with an LED driver?

I've never done any of this stuff before, but I've been reading up the past few hours on how to do some stuff my friend and I want to do for a project. What we need to do is be able to independently control 9 RGB LEDs. I know you can use 3 of the Arduino's PWM outputs to control a single LED, but there aren't enough outputs for 9. So after a bit of searching I discover that it looks like you need an LED driver, a separate device to effectively expand your number of outputs. My question is how would one connect the driver to the arduino and send signals to it? And secondly, using these two pieces of hardware, would I be able to light up five out of nine LEDs, each with a different color, and move them around at any given time? So I could light LEDs 1-5, then shift it over one to light 2-6? And be able to mix and match colors across the array. This is the driver I found: http://www.maxim-ic.com/datasheet/index.mvp/id/5261 And I was planning to use the Arduino Uno. Sorry for the noobness. I really have been trying to find information on this all day, but its difficult when you dont fully understand what the pieces of hardware do or how it works :) TIA!

It's not spelled out but it appears to me that the driver you have chosen has a single "Output Enable" pin for PWM on all ON channels at once. That would mean you can't cross-fade between colors. You also need 27 channels to control 9 RGB LED's.

The Texas Instruments TLC5941 allows for 4096 levels of light for each of 16 outputs. You can daisy-chan two of them to control all 27 LED's.

My question is how would one connect the driver to the arduino and send signals to it?

That depends entirely on the specific driver you use. Some use I2C, some use SPI and others need feeding with pulses, data and clocks that don't conform to any standard but just what that device needs. The TLC5941 and TLC5940 are popular drivers and are normally restricted to 16 channels. But you can multiplex them to drive more seemingly at the same time, this is one of my projects that does such a thing. http://www.thebox.myzen.co.uk/Hardware/Mini_Monome.html However there are many ready built shields and controller boards if you want to but rather than make.