Welcome to the forum Tina, you'll find the members on here are a friendly and helpful bunch :)
The two options you have is either replace the front seats with ones fitted with heated seats as standard. Or the other option is to have your seats dismantled and having the heater elements installed. Once either option has been chosen then you will need the wiring loom installed and switches fitted. This may require a different facia panel on the dash. It will also then be needed to be coded into the cars computer.
Either way it will be very expensive to retro fit the heated seats but it can be done.
Sorry I can't help more.
Cheers
Steve