Connect iMac to TV to surround sound?

[mnkyben]

Hi guys,

Looking to connect my iMac to my TV via HDMI, then play the audio through my surround sound system. I'm having trouble figuring it out.

iMAC: 21.5-inch, Mid 2011, AMD Radeon HD 6770M 512 MB (specs here)

Speakers: LG LHT888 with HDMI out only (specs here)

TV: TCL L40P60UF (specs here)

Thanks very much

 

[mnkyben]

Sorry, specs for the speakers here:
https/www.lg.com/us/tv-audio-video/pdf/h_lht888_spec_sheet.pdf

 

[mnkyben]

any ideas guys?