No need for the serial number, and the size isn't important either, but the model code is necessary. That's something that looks like UE55ES8000, for example.
Looking on the net shouldn't be necessary if you have the user manual. User manuals are meant for laywomen like you. Most often, it mentions the model number also.
Is there anybody out there please who can tell me how to install a microphone that can be used through Red Karaoke. I have looked everywhere on the net but even with the vast amount of info on the Samsung smart tv there is nothing to tell a layman or woman like me how to set up a karaoke mic or what mic to buy. I have the 51" one but can't find the serial number. Please help I would really appreciate it. Many thanks to you all.