Some computers, especially desktops, may have two video graphics array connectors, which will allow you to plug in multiple projectors simultaneously. If you're computer does not have dual VGA connectors, you likely will must purchase a piece of equipment known as a VGA splitter to divide the signal and allow it to play through both projectors. This will weaken the image, but as long as you split it only once, the difference will be barely noticeable.
Buy a VGA splitter. These can be purchased at most electronics supply stores and online and generally range from £6 to £13, though they can cost more.
Connect the splitter to the computer's VGA port. The VGA port is usually blue and has 15 holes for pins.
Connect the projectors to the split wires. Use VGA cables appropriate to your projector. If your projector's input is also a VGA port, use a cable with a VGA plug on either side, but if you are using a component projector, use a VGA plug with a three-prong output.
Power on your computer and projectors.
Calibrate the projectors. The way you do this will depend on your specific projectors, but you will need to set the input to run through your computer.