The Red/Green/Blue connection is called 'component'. It is the equivalent of the single yellow 'composite' cable; only video (obviously much better quality). Both component (R,G,B plugs) and composite (Yellow) cable are video only, and thus need the audio connections as well (typically red and white).
You plug the component or composite (component being the better choice, as it supports HD) cable into the projector, and the audio (red/white) into whatever you want to play your audio.
Okay,, thanks for your patience so far and taking the effort in responding to this... but as FAR as the projector I am stuck with... there is only one input for both video and audio. I want the component as its being the better choice, but how would I plug it? lol...also for audio...there's one input for it and its not for the red and white connections. Thanks again!