heres a quick break down.
your source(dvd plyer/ps2/ wahtever you want) has 3 outputs: 2 audio 1 video, your lcd will have a power and ground wire with a video input, some come with outputs to run more than one, your fm modulator have 2 inputs for the 2 audio wires from the source, the 1 video output from the source goes straight to the screen, then on the other end of the fm modulator is two antenna wires, 1 connects to the factory antenna wire behind the radio and the other goes into your headunit. And that is that.