In addition to the video cable, there should be a place for you to plug in for audio. You are responsible to supply your own laptop video and audio cables. This chart lists the video activation commands for common laptop manufacturers and models. I cannot get the screen to display computer, laptop, VCR, etc. Then make sure that the projector is set to display the correct signal.
Equipment is operable from the flat-panel, computer display.
My classroom has a Mimio whiteboard projection device. This device will allow you to project what you write on the whiteboard onto the screen overhead just as you would project the computer display. The Mimio is permanently attached to the whiteboard and you will find the special markers and an electronic eraser in the top drawer of the cabinet. You will find a Mimio shortcut on your desktop which you can delete if you don't plan to use this device. To use the Mimio, log into the PC computer, display the computer, and double-click the Mimio shortcut to launch that application.