It's a good idea to start out with a mermaid that you want to put a boulder under. You can work with the boulder first and then put the mermaid on, but you won't know quite how you want it contoured. So, having said that, create a new layer and name it "Boulder". Pick out a grey color and make a funny, boulder-y shape that your mermaid can sit on properly.
Next, dodge and burn around the rock. It doesn't matter how you do it, it just needs a little shading. Make it look semi-rock like.
Then, go to Filter>Pixelate>Crystallize. Mess around with the setting until the rock looks something like this. You don't want the crystal blocks to be too big or too small.
After that, if you'd like to add some moss pick out a green color and get a nice soft paintbrush and set the transparency of the brush to 30% or so and paint some moss on.
Now stick your mermaid on the rock.
You can add some little plants or something around the rock. Maybe try some sand or seashells or other animal life.
Here's how the finished product looks! DO NOT ADOPT THIS DOLL!
