Wire the tach signal wire to the Ranger's tan/yellow wire. You can find the T/Y at the PCM, the ICM, the instrument cluster or the tach service connector.
Most newer tachs can be adjusted to accommodate 4, 6 and 8 cylinder engines. This usually involves cutting a jumper wire or setting a switch. Some older tachs are specifically for one type of engine, so that's something to watch out for before you go to the trouble to install it.