Take a look at the electrical rating plate on the TV’s rear, which will list the power consumption in Watts.
To work out the cost of having the TV on for 1 hour, divide the TV power consumption Watts by 1,000 and multiply this figure by the amount you pay your electricity supplier for 1 unit of energy (1kWh).
My guess, and it is only a guess, given that we don't have any figures.
If it uses between 80 and 120 Watts, it would cost between 65p and 97p per day. My calculations are based on a unit cost of £0.34 per kWh. That is if you have it turned on 24 hours a day.