Autodesk Revit Architecture

[#1]

Can someone tell me why the Layers icon on my tool bar is faded - I can't access it to create layers.

Just started Revit - I'm stuck on "can't create layers" because the icon is not "active" or something.

HELP !  Someone please write back so I can keep moving forward with training.

Thx

[#2]

Please define what you mean by "layers" in Revit.

[#3]

I actually mean levels

[#4]

The level tool becomes active in elevation or section views, and inactive in plan views.