Before getting started, turn the volume all the way down on the home audio system and then turn off both the home audio system and your PC. Plug the headphone end of the cable into the corresponding jack on your PC. This is typically a light green jack, but may be a different color or not colored at all. Make sure it is the headphone jack. Next, plug the RCA ends of the cable into the home audio system. Make sure you plug the connectors into Input jacks and that the color of each connector end matches the color of the jack in which it is inserted. For example, the red connector should be plugged into the red-colored jack, and so on.
Turn on the PC and then turn on the home audio system. Open a music file on your computer or find some streaming audio online. Choose something that will play for a while so that you can have time to adjust the volume and other settings on your home audio system properly.
Turn on the home audio system and select the proper setting depending on which input the RCA cable is connected to. For example, if the input says "AUX," be sure to select the home audio system's auxiliary option. Gradually increase the volume on your home audio system and make any other changes you desire.