If not, then the TV goes into that and you only need a coaxial cable. Any old RCA cable will work, but there are cables specifically for digital coaxial audio.

The digital out is in the lower-right corner of the inputs. It is labeled "Digital Audio" in the manual (pg 17):

http://files.sharpusa.com/Downloads/ForHome/HomeEntertainment/LCDTVs/Manuals/mon_dow_LC42SV49U.pdf

If you are using it, then you will need a coaxial-to-Toslink converter:

http://www.monoprice.com/Product?c_id=104&cp_id=10423&cs_id=1042302&p_id=2947&seq=1&format=2

You will need a Toslink cable and a coaxial cable with the converter.