Tell the typical design process, schematic capture to capturew the schematic, use of the device libraries for defining various devices, routing the PCB, mention the difference between the auto routing and hand routing. Then generating the CAD files.
Include links to other sites describing PCB design; and more importantly to PCB design tools.
Description of the gerbaerformat, specific details of the format used by us. And the names of the Drill files and the Aperture files