I can't get sound through my headphones on my Bravia kdl-52xbr5 tv. First time I have tried to hook up the headphones which are sharper image wireless

I take it the headphones are charged up and known to be in good working order? Are you using the 3.5mm headphone jack on the side of the TV or the white and red RCA jacks labeled AUDIO OUT (VAR/FIX)? If using the headphone jack the TV should shut off the internal speakers and output to the headphones. If using the mentioned RCA jacks you need to go into the audio options settings and set to Audio System. Also under audio settings, Audio Out, you can pick Fixed or Variable. If you opt for Fixed you will use the headphones to adjust the volume. If you opt for Variable you can control the headphone volume and muting using your TV remote control. Just make sure you have the headphone volume turned up adequately.