Trying to get sound from laptop to tv please hekp

Hello, i have a toshiba lap top and a lg flat screen 50 inch tv well i hook up my hdmi cord to my tv picture is perfect but no sound,only sound i get is out of my comp or speakers i have hooked up,I went into control panel went to sounds right clicked said show disable but nothing then someone else said do the same thing and you should see something that has hdmi in there well theres nothing at all on my comp that has hdmi i went in and clicked on tv got green check mark nut everything else is greyed out some one please help getting so frusterated ready to give up