PE5 Layers Don't Work?

Okay, so I've had PE5 since last Xmas, and I'm still getting used to it. I might just not be doing something right, I don't know. But basically when I create a new layer, I can't change to other layers or anything... I've basically given up on them. Maybe there is something that I'm meant to do but I'm not? or maybe it's because I use an Apple Mac? Could someone please help me here because I'm a bit stuck...