Val, Bob had pretty good instructions, but a couple things may need clarification. First, on most computers, the headphone jack doubles as the "line out" jack, so that's what you'll probably plug into to get the sound out to your receiver.
On the back of your receiver you'll need to fine a free "aux" or audio input. These will be RCA jacks, and for audio they come in pairs. There's a red one (right channel) and a white one.(left channel). On older receivers they may not be color coded, but labeled R and L instead. Make sure it's an input and not an output. (NOTE: there may be a third yellow input which is for video, you can ignore it in this case.)
You'll need a cable with a stereo mini plug on one end and two RCA plugs, one red and one white, on the other end. Here's what they look like. http://www.amazon.com/eForCity-3-5mm-Auxiliary-Cable-Cord/dp/B0042DIZTE/ref=sr_1_19?ie=UTF8&qid=1418973108&sr=8-19&keywords=stereo+rca+to+stereo+mini+plug+cable They're pretty common and you can find them in the electronics department of any big box store or Radio Shack, and even drug stores.
Then just plug the mini plug into your computer's headphone jack, and the red and white RCA plugs into your receiver, set your receiver to the appropriate input and you're set.
