Just connect your PC or laptop vga (monitor) out-put to the vga input of the projector - the projector will then be a big version of your monitor - if you are using a PC you will lose your monitor and if you are using a laptop you'll need to select output to external monitor (usually press function F5 at same time will do this). The cable you need will be an HD15- male to male - available up to 30 metres long. We do this all the time at home - great fun.