Grid lines cannot be displayed in the viewfinder of your camera. To show the grid lines, you need to replace the focusing screen with the separately sold Focusing Screen Ef-D (with etched grid lines).

For details on the focusing screen, please see the instruction manual supplied with the camera.

Also, for procedures on how to replace the focusing screen, please see the instruction manual for the focusing screen.

In addition, for Live View and movie shooting, you can show the grid lines on the LCD monitor.