I am not familiar with working with layers. I tried to learn about fading the edges of a photo. In the process I did something with layers that I can't undo. Now when I draw a object I only see the dotted outline and I can't see the fill, etc. I know it must be on another layer but I can't find it. How do I just go back to how it was with just one layer?

Click on the "eye" icon next to the layer's name to toggle its visibility back.