If a shape is not already assigned to a layer, the shape is automatically assigned to the active layer when you drop it on the page.
For example, if you are going to add electrical wiring shapes to a drawing of an office layout, you can make the electrical layer active. All the shapes you add from then on are assigned to the electrical layer. When you begin to add windows, you can designate the wall layer as the active layer.
If shapes need to be assigned to multiple layers, you can designate more than one active layer. Shapes you add to the page are automatically assigned to all of the active layers.
Activate one or more layers:
On the View menu, click Layer Properties.
For each layer you want to make active, select the check box in the Active column.
The layer is active for the current page. When you drag a shape that does not have a predefined layer assignment onto the page, it is assigned to the active layer. Making a layer active is a fast way to assign shapes to a layer as you add them to the page.
Note: You cannot activate a layer that is locked against editing.