how to do this...

I came across this and I'm curious about how it's done. It's prolly a simple tihng but I dont know it. Also, if anyone knows, how to add onto something like that to make it look like the light is like bursting out of one of the cracks. Thanks.

•Filter > Render > Clouds
•Filter > Texture > Stained Glass
•Invert (CTRL+I)
•Levels (CTRL+L), drag the top black slider along until most of the grey is black or very dark
•Filter > Blur > Gaussian Blur (about 2 pixels, depends on the settings used for the stained glass)
•Make a new layer
•Choose black and bright green (or whatever colour) as your foreground and background colours
•On the new layer, Filter > Render > Clouds
•Set the clouds layer's blending mode to overlay.