First check to make sure you have coolant fluid in the radiator, if you have no coolant then you will not register any temp. If there is coolant then replace the temperature sensor. If it moves some as the car warms up, say to halfway to the first mark (1/8 scale), it might indicate that the thermostat is stuck open, not allowing the engine to warm-up to normal operating temperature. That can result in increased tail-pipe emission, reduced fuel economy, and poor heater perfromance in winter weather.
The light you are describing indicates low coolant level in the coolant reservoir.
You need coolant.
Check your coolant level
Low coolant
On the bottom right of the dash, looks like a box of explosives with a push down lever, with a an arrow pointing down at a wavy line
Engine coolant temperature switch/sensor
Coolant low or sensor may be off.
The sensor is threaded into the coolant passage in the back of the cylinder head.
on the right side of the engine
Engine Coolant Temperature Sensor.
Start by replacing the Engine Coolant Temperature Sensor
Refer to the link below