Cool - it does have a digital audio output (I'm assuming that you meant LC-
42D62U, as you said it was a 42" TV). It's an optical connection, and your receiver has one open optical input left (the other one is being used by the DVD player).
You'll need an optical cable to make that connection. I've purchased
these from Monoprice.com, and they are well made and work great. You can get optical cables at a lot of places, though. I wanted to show you those from Monoprice to give you a feel for the cost. You don't need to spend $20+ for one.
Do you have a spare optical cable around? You could always use the one that's connected to the DVD player just to try out surround sound from the TV if you don't have another cable at the moment.