what do the wire colors on alternator wire harness mean ?

It goes back to the computer-see below

so on my carbed prelude will this alternator work? if so then where should i connect or splice the extra red/white wire to make it work? should i just leave it hanging?

You can ignore it-and check the running voltage of the alternator if its correct

on my other post about this problem they said it wont work....so will the fi alt still work on my carb prelude?

The wire you refering to goes back to the computer as indicated in the picture which controls the alternator's field generation circuit-

so will it work without that wire plugged into anything

As mentioned in the earlier question, it will not work as designed, i feel that it will do one of two things, not work at all or go to an over charge state, which can do serious damage to electrical systems, the colour coding is just to distinguish which wire goes where on the schematic, i would suggest that you get your old alt overhauled and avoid the possibility of doing any damage.