This is a very easy project.
Here is the result
But you should be able to make it work with the information given on this instructable.
Step 1: Prepare RGB LED strip
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.
Read more: Make your own TV ambilight using Arduino