Four pin relays are all you need. The fifth pin is unused. The 5th pin provides power when the relay is not activated. You don't need to do that.
http://www.autoshop101.com/forms/hweb2.pdfYou install the relays so the bike's wiring turns on the relays instead of the lights by sending current to the relay coils via their two low current connectors. Then the relay's high current side closes. The two connectors on the high current side complete the delivery of current from the battery positive to the light. All that is needed to complete the circuit is an earth connection to the battery negative. Do a Google image search for headlight relay wiring and you'll see plenty of diagrams.
