You will have to install the sensor and connect the green wire. This gauge is also for Negative earth vehicle so also check your negative battery terminal does in fact connect to the chassis / engine.
Suggest test it off the vehicle with the correct sensor.
As a minimum you will need 12V+ve on white wire, and 12V -ve on the sensor body and green wire connects to sensor terminal.
After that you can add in the black wire to 12V-ve, 12+ve to red wire and finally 12+ve yellow wire for illuminating the gauge