Can someone tell me how layers work in art programs? I'm really new to using computer programs and I've seen people talk about layers, so how do they work?

Layers are just that, layers. Think of them as like stacks of clear paper on top of each other. Here's a boring but thorough tutorial on layers in photoshop. It's the same concept in most other art programs.

http://www.youtube.com/watch?v=d9Rbl75P0mQ

Thank you for the link I think I understand it better now :]