Creates matrix style from the film backdrop, animated green on black.

I wish to add this canvas as a background to my personal webpage. The code is beyond my understanding. I understand only how the characters are chosen, and the colours, but not how they are displayed. The html elements for my personal webpage will be enclosed in a container-div, which be positioned centrally on the screen and have a higher z-index value over the canvas element. The canvas will have a lower z-index than the div. My webpage nav buttons should appear over the matrix effect background.