Here u will learn how to make this:

Step 1:
Open a new at least 100x100 (or whatever u want) pixels with a white bg also pree 'D' to reset your colors. . Now go to Filter-Texture-Grain with settings: Intensity:100 Contrast: 100 Grain Type: Vertical.
Step 2:
Next go to Filter-Artistic-Neon Glow with settings: Glow: 5 Glow Brightness: 20 Glow Color: 00FF00
Step 3:
Now basically your done, just go to Filter-Stylize-Glow Edges with settings: Edge Width: 1 Edge Brightness: 5 Smoothness: 1
And that's how u make a matrix background[SIZE=1]
I'm sooo sorry for the big pic :unsure: