Look for the analog audio out at the back of the TV? Check your manual - should be red/white RCA me thinks so you'd need a RCA-to-3.5mm female cable. Alternatively if your TV has headphone out try that
Most TVs have only an optical digital audio output so if your speakers don't have this connection you will need to convert the optical digital to analog L/R audio with a converter like this: http/www.amazon.com/Orei-DA34-Digital-5-1-Channel-Headphone/dp/B008EPW7O0
You will have to adjust the volume on the speakers however since the TV output is usually fixed in level.