Luckily, this time it will be easier done than said and you really do not have to know the whole theory in order to make fascinating pictures. We can use an LCD monitor as a source for polarized light and all you'll need is a camera and a polarizing filter.
Step 1: The Setup
For the polarized light source, I put a portable computer flat on the stand and opened a white screen (e.g. in a web browser or word processor).
Next, you'll have to turn the polarized filter until no light is transmitted to the camera. You will see that the white backgound turns to black. It's my personal preference, but I think it looks better with a black background.
Step 2: Take Pictures
Adjust focus and exposure time on your camera. I can not give you hints here, it is a matter of trial and error.
As an example, you can see a cookie packaging plastic without and with polarizing filter.
Step 3: Take More Pictures
But aside of all the science, the pictures are nice to look at...