may i know how to book a taxi in advance from lijiang airport to old town ruo shi guang liu ying lodge?

It is not necessary to book the taxi in advance. You can find many taxis outside the airport to reach the old town and you can easily hire one.
Upon reaching the gate of the old town, you need to walk to reach your lodge, because the cars are not available to enter the ancient town.
The taxi fare to reach the ancient direct is around 100RMB.