If you have internet connection- below is a great video to fully explain a projector and laptop set-up.
Connect laptop to projector.
Connect the VGA cable from the laptop to the projector!
(note: New netbooks do not have a VGA out. You must use a laptop or desktop computer.)
Turn power button on, on the projector first. Then make sure the projector is on the correct input. See which input # the VGA cable is connected to on the projector. Projectors will have either a input or source button. Pushing this button will roll thru all the inputs untill you reach your input#.
Turn your laptop on. Typically now, the laptop will automatically output to the projector in windows dual mode and the screen will show on both the same.
If not - you can also hold down the Fn (function key and press the F key that shows the picture of a screen or says LCD. On some models - pressing this button again will roll you thru 3 or 4 different styles of- (dual mode, projector only, extended mode, laptop only)
Ocassionaly laptops will drop the output driver and you may need to try another laptop.