A sound bar is a long speaker that typically is set at the base of a television. The speaker sound bar usually connects directly into a television, however, you can also plug it into other devices that produce audio, including a cable box and DVD player. If you want, you can connect both the cable box and DVD player into the sound bar, even though a sound bar typically has only one audio input.
Plug the RCA audio splitters into the red and white RCA "Audio In" ports on the back of the sound bar. The male end of the splitter cable inserts into the port. The other end of the splitter has two different female connections. This allows you to plug both the cable box and DVD player into the same audio port.
Plug the red and white RCA audio cables into the cable box. Run the other end of the cables to the audio splitters. Plug the cables into the correct colors of the audio splitter.
Repeat the process with the DVD player. You can now listen to both devices over the sound bar, however, do make sure to only have one device on at the same time, otherwise the audio from both play simultaneously over the sound bar.