on an LG flatron,where dio you plug up the speakers on audio input?

Answer 1

Speakers are always plugged into the "Audio Out". Read your owners manual to see if the audio-out is amplified or not. If it is, you'll need to know the maximum output wattage. If they aren't, you'll need to plug the audio-out to your amplifier's "Audio In". And then plug your speakers into your amplifier's speaker outputs.
When all else fails, read the manual.