Open a new image
1. go to Filter-Texture-Grain (intensity:100 contrast:100 grain type: vertical)
2. Set black as forground green as background
3. Filter-Artistic-Neon glow (glow size: 7 brightness:50 glow color:black)
4. Filter-Stylize-Glow edges (edge width:1 edge brightness:8 smoothness 1)
Voila a Swweet Matrix Backgorund