Layers are the bread and butter of SpriteMancer. Every tool available (except the Node Graph) needs to be in a layer.
To create any Elements, you can right click on an empty space in the Layers section and a Create popup will appear. You can then select any of the included Elements to be created in the selected layer (in case of Particles or Models) or in a new layer.
In SpriteMancer, the tools are called Elements:
Layers can be dragged around and moved freely. The order of the layers affect the render output and they are sorted in a way that top layers are rendered last.
Right clicking a Layer show its context menu. The content of the context menu is different for each Element but they all have a Blendmode option included. This allows layers to be Additive or Subtractive.