Finding your MAC address varies from manufacturer to manufacturer. For more specific information on how to find the MAC address for your device, please consult your device's documentation.
For your convenience, here are links to the support pages of several popular TV manufacturers support pages:
Note: MAC addresses appear alpha-numeric codes (i.e. a1:b2:c3:45:d9:aa). The addresses will appear in combination of letters and numbers differently for each device. It does not matter if you enter the alphabetical letters in uppercase or lowercase.