Cool project!!!!
But since this will be my first Andruino and electronic project...
If you haven't done any programming, you need to learn a little programming and a little electronics.
I'd recommend you start with some of the simple [u]Examples[/u]. The examples show you how to hook-up and blink an LED, and how to hook-up and read a pushbutton switch, etc.
PROGRAMMING
The delay() function that's used in the Blink Example probably won't work in your actual-final program. The delay() function pauses execution during the delay time, so your program can't respond to switches/buttons, or your gyro, etc, during the delay time. Most real-world programs avoid delay() or they only use very short delays carefully... You'll need to use the methods from the Blink Without Delay example (also explained in the post at the top of teh forum about doing several things at the same time.
The two most important concepts in programming are conditional execution (if statements, etc.) and loops (doing something over-and-over, usually until some condition is reached). Once you understand those two concepts, you're on your way to understanding how to put a program together.
HARDWARE - ELECTRONICS
There are two categories of LEDs. There are "regular" or "standard" low-power LEDs, and this includes RGB LEDs and "high brightness" LEDs. You can drive one or two standard LEDs from an Arduino pin (with the required current-limiting resistor in series).
During development, you can use a few regular LEDs and drive them directly from the Arduino
But, for your final project you'll want more LEDs or high-pwer LEDs.
If you want to drive several regular LEDs, you'll need a transistor or MOSFET for each "channel' (for each color, or for the left & right sides, etc.).
High-power LEDs (1 Watt or more) require a special constant-current driver. These are tricky to build, so if you end-up choosing high-power LEDs I'd recommend buying driver boards rather than building them yourself.
You'll probably need to do some "outdoor experiments" to see if you can get enough light from a cluster of regular RGB LEDs, or if you need to go high-power. If these are supplemental to your existing lighting, it might not be so critical, but if these are replacing your existing lights, it's very critical...
For experimental purposes you can power-up regular LEDs with just a power supply (or motorcycle battery) and current-limiting resistors. There's no need for the transistor/MOSFET if your are not controlling them from the Arduino. High-power LEDs require the driver, or you could actually get-by with a high-power current-limiting resistor.
I don't know anything about (real) gyros with microcontrollers... A true-gyro should work, but a basic solid-state accelerometer might not work, because when you turn you lean so from the bikes perspective there is no left or right force... The cornering forces push you straight "down" in the seat, not off to the side of the seat. And, I agree it's a real-good idea to save that part of the project for later... 