Connection Setup
To connect your PS3 to your TV with a composite cable, you'll use the port on your PS3 labeled "AV MULTI OUT." This is a multi-purpose port that supports several types of video output. After you insert the cord into that port, you just need to connect the other end to the TV by matching the colors of the cord connectors to the colors of the composite jacks on the television. In this context the term "composite" is synonymous with "RCA," so if your TV lists "RCA" in its manual or next to any ports, that means they're composite connections.
PS3 Settings
The PlayStation 3 has options for standard-definition output that any TV can use up to full 1080p output that a quality HD television accepts. Composite connections only support standard-definition, and you should step through the PS3's setup for that connection type. If you turn on your TV and find that you can't view anything at all from the PS3, you may need to reset the console's video output by pressing and holding the power button while the PS3 is off; you should continue holding the button until you hear two beeps, which means the output has been reset. You configure the picture by going to "Settings" in the XMB menu and selecting "Display Settings," and then "Video Output Settings." Select "Composite / S Video," and then select your TV type based on its aspect ratio. The "16:9" option is for widescreen TVs; "4:3" is for the traditional 4-by-3 ratio. Those TV have screens that are only slightly little than they are tall.
Composite Information
TVs and other products have been using composite connectors since the 1950s, and at its invention it was a good method for sending color video to a display, which was a new option for select TVs. You can use composite cords for a TV with a 4-by-3 or 16-by-9 aspect ratio, but the image will remain "standard-definition" either way. Composite connections nearly always use two visually identical RCA cords and connectors for audio, though you could use a different setup if you wanted, like a Toslink connection for surround sound. When you connect your PS3 to a TV using a composite setup, the console can output a maximum 480i resolution and use your choice of stereo RCA audio or Toslink, which the PS3 terms "digital out" and "optical digital."
Other Options
The PS3 supports video resolutions for games and movies up to full 1080p. Composite cords are incapable of transmitting high-definition video, so you'd need to use a different setup if you want to take advantage of the PS3's HD capabilities. The best option is HDMI, which bundles HD video and audio together, even supporting 1080p resolutions and 7.1 surround sound. Another option is component, which uses three connectors on your TV colored green, blue and red, though often they're labeled as "Y," "Pb" and "Pr." Those three connectors are only for video, so you'd need to use an RCA or Toslink connection for audio.