You can find the Layer Tab on the RollupBar. On the Layers tab are a few useful buttons and the layer list. By default, the levels level's objects will be located on the "mainMain" layer.
In the screenshot that several layers have an asterisk after them. This shows layers that have had changes made to them.
Be sure to enter a useful and recognizable name for your layer, possibly indicating its function or a description of what it contains. For example "beach area" or "sounds".
In the dialog box you can also specify if the Layer is visible, is frozen, Export Layer Pak, Default Loaded, is external, will be exported to the game, or Brushes Have Physics.
Also you can specify which platform to export the layer to. Default = Export to all platformSee the Layer Settings description for more information on the functionality of each individual setting. You can always change these settings later on by clicking the Layer Settings button or right-clicking the layer and selecting Settings.
Deleting a Layer
Click the Delete Layer button to delete the currently selected layer. A dialog box will show up and ask for confirmation.