Did you click on Layer Settings? If not, the list of "predefined layers" you see under Document>Layers are not layers at all, they are Layer Combinations. ie. Drafting, All Visible and Unlocked, Enlarged Plan, etc.You use these to show specific combinations of layers for different views.
The actual list of layers are found in Document>Layers>Layer Settings or Ctrl+L(Win) Command+L(Mac). If you start a new file using the ArchiCAD Template the project will be populated with a list of predefined layers, which is good fro just jumping into the program at first, but I recommend you customize your own list of layers and even better, start from scratch with no template. It is a lot of work, but once you make the layers your own you will have a much better time working in ArchiCAD.
Here is a video overview of layers:
http://www.youtube.com/watch?v=f3qz4m2WsmE