the wiring is left =high top=low right=common (earth)
if you mix the common and the high , then the circit runs thru both fillimants and produces a dim light if you mix , the low and high wires you switch will be reversed .
you "should" be able to get the matching plug , to extend your loom from an auto shop , or a car breakers
most bikes (in the UK) have a smaller pilot light below the main bulb , dating back to the days when we had to leave a light on , when parked at night , not sure about the american bikes , but in europe the switch has off/side (pilot)/headlamp , then the dip/main switch alongside
again , in the UK , we drive/ride on the left , (most of europe is on the right) , and as such our lights dip and cutoff to the left ,