Oh gosh, I'm horrible at explaining. BTW, the layers are in the bottom right corner of the Oekaki.
Basically. they let you draw on different layers. Like, you can have a white background, then draw the lines of something -Crow, let's say- on a different layer. Then you can add a layer between the background and the lines that's just for Crow's color/fur. Since the fur layer is below the lines, you only have to color it in and stay in the lines. But since the fur layer is above the white background, it appears above the white. If you removed the fur layer, everything would stay except for what was on that layer.
That was a horrible explanation. Let me try again:
If you color a background
red, and make a few layers above it, those layers are clear, so you can still see the red. On the layer right above red, you draw
blue stripes across the picture. On the layer above that, you put a small
purple ball in the center On the next layer, you add a big
yellow blob right in the center. On the last layer, you draw a
green zigzag stripe coming down the picture.
Take off the yellow layer by clicking the little dot next to the name of the layer (Click it again to put it back on). The name can be changed by double-clicking the name.
Remove red, and everything stays.
Put red and yellow back on, and remove purple and blue. Ta-da!
Wow, I can't explain. So I added pictures!