Press green flag, wait* till the image is rendered, then* move your mouse on the stage (wait a bit, till you move it again for the image to render). Its rather slow, you might want to try it on turbowarp: turbowarp.org/1014000233 I made it possible to import your own normal map and texture now.
I got the normal map and texture examples from https://opengameart.org/content/brick-wall Credits to @gubbensteve and @griffpatch for the image scanner: https://scratch.mit.edu/projects/964710216/