Carnation

I've been playing about with Photoshop Elements for hours and progressed little!! The trouble is that I use a PC at my course but a Mac at home and I can do most tasks at the Course but, when I come to try these at home, I don't seem to have much success!! Any ideas? I can't even understand most of the 'Help' answers so anything would have to be explained VERY simply!
Meanwhile I'll keep on trying to understand these layers!!!