http://kanri.info/suzuki-ltr-450-wir...ing-diagram-at
Earth wire is black and white, you can check by looking what colour wire goes to the larger blade on the bulb (the one at 90deg to other two ).
At bottom LH of diagram you will see 'dimmer switch' shown, this is the handlebar switch that switches from dip to main beam (the switch positions
are marker 'hi' and 'lo' for main and dip) - follow yellow and green wires on the diagram (not that colour on your bike though, just highlighted for
ease of reading on the diagram).