Help needed to wire Nest 2nd generation Thermostat

I would like to replace my old Honeywell non-programmable thermostat with a Nest 2nd generation. My current thermostat has the following wires: Green wire on G Cyan wire on C Red wire on R Yellow wire on Y (and W1 via a jumper) White wire on W2 Orange wire on O How should these wires connect to the Nest which has the following connectors: