This is a very easy project.
I won't go into too much detail how each part works, because I have written some information on my blog.
But you should be able to make it work with the information given on this instructable.
Here is the result
Step 1: Prepare RGB LED Strip
The RGB LEDs came as a strip, but I want them to be separated further, so I soldered wires in between. I also use hot glue to strengthen the soldering points.
you could buy led strips that have long cables, or you can just use this out of the box, it's up to you.
I am using 25 LEDs.
Step 2: Mount LED Strip on TV
My example is a bad one. you should be more accurate about the LED positions. and the should be facing outward with a angle, so the Lights can be seen brighter from the front.
The sketch is how the LEDs should be mounted on the TV.
Step 3: The Connection (Arduino, Power)
The good thing about these LED strip is, it only requires one data connection from the Arduino.
You have to use external power source. I am using a 5V 2A power adapter for this.
Note: GND of the power source should be connected to the Arduino GND.