You'll need to see whether you have the SWM wiring setup or the older 2 wire setup. How to tell? Glad you asked. If you have an HD receiver or DVR just press the <dash> button right below the 7 while you are watching normal TV. If you have the new single wire setup, it will say "SWM Connected" in the pop up box. If it doesn't say it, you have the older setup.
If your box is an SD DVR, check and see if you have 1 or 2 cables at the Sat In ports. If you are SWM, then you will have just a cable at SAT 1 and SAT 2 will be empty.
If you have just a SD receiver, you'll need to check for a little red filter at the SAT-In port or locate your SWM Power Inserter. That's a little black box about the same size and shape as a chalkboard eraser...