A computer is what is usually connected to a projector, for presentations. But a projector can also be connected a DVD player if you wish to show movies on a screen larger than your TV's. Just how large depends on the projector you use.
Insert the yellow RCA cable (or S Video Cable) into the "Out" port of the DVD player. Plug the other end of the cable into the "In" port of the projector.
Power on both the DVD player and the projector.
Press the "Menu" button on either the projector or the projector's remote control.
Select the video setting and chose the DVD player from the available input options. You will now be able display your DVD images through the projector. Do this by selecting the "Video" input (there will be other selections such as "Computer" and "VGA" options).
For sound, connect the red and white RCA cables to a set of speakers. These cables will be run from the "Out" port of the DVD player. If you want you can connect them to the "In" port of your television for sound, or a stereo music system.