2D Animation & Compositing

I am wondering what the best ways are to composite sequences of images together in blender? I’m attaching a screen shot of my node setup right now… obviously it’s not working out too well. Is there a better way to tackle this? I appreciate any help/ideas you guys have.
thanks!

http://www.fantoccini-inc.com/tutorials/complayers.jpg

I assume you want your characters opaque on top of the background. In that case you need to use Alpha Over nodes (Add->Color->Alpha Over) instead of your Mix nodes. Make sure when you add the background it goes to the top plug of the Alpha Over node, and your combined sprites to the lower plug. At least that’s how I remember it.

thanks! I realize now that I was thinking incorrectly about the inputs of nodes in blender and relating them to layers in a top to bottom order but really it appears that the bottom node is first. Thanks for your help!