Welcome to the forum, visch1!
As TLS asked, please let us know your TV model number so that we can check the connection options.
Odds are that the TV has an optical digital audio output. If so, then the cable that you want is like the one pictured below. You can get them at several online retailers, and I suspect that you'll also have several local stores that carry them. Monoprice.com is a good place to buy most cables, as their prices are quite reasonable, but there are other good options. You shouldn't have to pay more than ~$5 for a six-foot cable.
End of cable
Full cable