In a drawing, click Layer
Properties 
on either the Layer toolbar or the Line
Format toolbar.
The Layers dialog box appears.
Click New, and enter the Name of a new layer.
You can create layers in a SolidWorks drawing document. You assign a line color, line thickness, and line style for new entities created on each layer. New entities are automatically added to the active layer. You can hide or show individual layers. You can move entities from one layer to another.
Dimensions and annotations (including notes, area hatch, blocks, break lines, detail circles, section lines, and tables) can be moved onto layers; they use the color specified for the layer.
Sketch entities use all the properties of the layer.
Components, in either part or assembly drawings, can be moved onto layers. The Component Line Font dialog box includes a list for selecting a named layer for the component.
If you import a .dxf or .dwg file into a SolidWorks drawing, layers are created automatically. The layer information (names, properties, and entity locations) specified in the system where the .dxf or .dwg file originated is retained.
If you export a drawing with layers as a .dxf or .dwg file, the layer information is included in the file. When you open the file in the target system, the entities are on the same layers and have the same properties unless you use mapping to redirect the entities to new layers.
To create a drawing layer:
In a drawing, click Layer
Properties on either the Layer toolbar or the Line
Format toolbar.
The Layers dialog box appears.
Click New, and enter the Name of a new layer.
NOTE: If you save the drawing as a .dxf or .dwg file, the layer name may be changed in the .dxf or .dwg file as follows:
All characters are converted to uppercase.
All spaces in the name are converted to underscores.
Specify the line format for entities on that layer as follows:
To add a description, double-click in the Description column and type text.
To specify the line color, click the Color box, select a color, and click OK.
To specify the line style or thickness, click in the Style or Thickness column, and select the desired style or thickness from the list.
Active. An arrow 
indicates which layer is active. To activate a layer, click
beside the layer name.
On/Off. A yellow lightbulb 
appears with any layer that is visible. To hide a layer,
click its lightbulb. The lightbulb turns white 
, and all
the entities on the layer are hidden. To turn the layer back on, click
the lightbulb again.
Move. To move entities to the active layer, select the entities in the drawing and click Move.
Delete. To delete a layer, select the layer name and click Delete.