We hooked it up and have no sound - Microsoft Xbox 360 Console

Know whether you have a analog/digital or Dolby signal to what component you trying to use or hook up to

From the Console Settings screen in the System area of the Xbox Dashboard, you can configure the video output of your Xbox 360 console for a widescreen, high-definition TV, determine your audio options, and check your console's serial number and Xbox Dashboard version.
Go to correct section for ... Audio

Change your audio output settings for games from this screen. These audio settings do not affect DVD movie playback. For DVD audio settings, refer to an individual DVD movie's setup screen.

Settings consist of:

• Analog Output Settings: choose Mono to merge the left and right audio signals so that you can hear all sound through a connection to a monaural TV or monitor; choose Dolby Pro Logic II to listen in normal stereo (no audio surround receiver required) or to listen to Dolby Pro Logic or Dolby Pro Logic II soundtracks from compatible games or other media.
  
  Dolby Pro Logic consists of four channels of audio: front left/center/right and a monaural surround channel that is mirrored in each of your rear left/right speakers. Dolby Pro Logic II uses digital signal processing to generate 5.0 audio (front left/center/right, rear left/right) from any stereo (left/right) programming, whether from movies, music, or games. Unlike movies and music, however, games are specially encoded with Dolby Pro Logic II decoding in mind.
  
  To listen in either Dolby Pro Logic or Dolby Pro Logic II surround sound, you must connect your cable's left/right (white/red) RCA connectors to a compatible surround receiver. For more information, see our connection page for the cable you're using:
• Digital Output Settings: configure this setting only if you'll be using the Toslink optical digital-audio output from a compatible Xbox 360 AV cable (optical digital-audio cable sold separately):
  
  
  The default digital-audio setting is Dolby Digital 5.1. If this is your preference, you do not have to make a selection from this screen.