Left click the new layer's blend mode of Normal and change to Lighten. Crop the image at this point to get rid of the light band on the top and left. In the layer palette left click on Normal blend mode for Layer 1 and change it to Overlay. Fill this new Layer 1 with a pattern or color you want the etching to be on. Marble and wood patterns work well.
Plain colors do too.
I am still trying to get what I think is a good glass look. If you have textures or filters for making glass blocks, you can use them on this layer. Anything that makes this layer look like a block will work. That's the basics. You may find that some color and textures need to have the slider moved a little to look like you want.