Here's what I would do.
Find a background of some sort of nature place, maybe a dojo landscape. Something MK-esque.
Using the pen tool, outline the entire backdrop (everything but the sky) and make it black. Gaussian blur that vector shape to give it a faded look, then select the sky and give it a red hue. If you wanted, you could change the highlights of the cloud to a darker color to make it look more dismal.
Also, I cannot stress enough the pointlessness of the lasso tool. The lasso tool is only good for selecting parts on an object, not for outlining an object. Use the pen tool for that, it's alot easier to work with and in the end you have a very nice looking edge. Here, because I'm not busy, I'll show you.
Let's take this image of ermac:
Now, I'll post a comparison of the lasso AND pen tool:
It's pretty apparent that the pen tool is something that is there FOR YOU. Please, in your next "wallpaper" do not use the lasso tool. Thank you.