Layers

To insert a new bitmap layer use the button just to the left of the garbage can icon.

To delete a layer, select it and hit the Delete key or the garbage can icon at the bottom right of the Layers panel.

To rename a bitmap layer, double-click on the name of the layer "Bitmap" and type in something. Then Enter to apply/set the name.

To insert a new layer folder, click on the button at the far left of the bottom of the layers panel. Make sure you don't your first default layer locked!

Whatever you do, don't click on the "New Sub Layer" button!

You can lock layers to protect all the layers in that layer folder...

You can show/hide everything in a layer folder by clicking on the eyeball...

You can change the layer blend modes and opacity (% how much is visible)at the top of the Layers panel.