This is posted under the Sony STR-DE685 heading, so I assume that's what you have. (If not, your receiver may have other hookup options available.) It might help if you download the manual if you need a copy from Sony's site here
. It details all the rear panel connections.
This receiver doesn't have HDMI connections, so you'll need to make your connections using RCA cables It doesn't pay you to get an HD cable box if you're planning on connecting it through the receiver.
Output to the TV is very simple. Use a component video cable to go from the component monitor output on the receiver to the TV's component input. Then switch the TV to that input, turn off its speakers and listen to the sound through the receiver. Only one cable going to the TV that way.
Inputs will need separate audio and video connections since there are no HDMI connectors. Use the component video connection for your DVD player for the best video quality. The DVD/LD input offers those jacks. You can connect your cable box to the VIDEO 2 input using component video connections (if the box has those outputs) or composite video. Then the video and audio from the box will run through the receiver as well.
If you want to get a new HD cable box, you'll need to run a cable from its HDMI output to an input on the TV, and switch the TV to that input to watch the box. You can still run the audio signal through the receiver though. That will add one more cable to your hookup, and you'll have to remember to switch inputs.
Hope this helps. Thanks for using Fixya!