Audio dubbing

I am wondering if there is a program for MAC OSX/Final Cut, that will allow me to put vocal tracks (my own narration) into Final Cut?

Do you need to record it, or is it already recorded?

If you need to record it, look into the Voice Over Tool in FCP. You can find out how to set it up and use it in the help menu of FCP. Type 'voice' in the search bar at the top right. Of course, you will need a compatible microphone.

If your voice has already been recorded elsewhere, just put it on the timeline like any other audio. Make sure it's an aiff at 48khz for ease of use.

GarageBand, Soundtrack and Final Cut Pro (Voice Over tool, as Jude mentions) all have recording capacity. The latter two will allow you to watch your footage and loop it at the same time as recording, an obvious advantage. You'll need an audio interface of some sort, if only a Griffin iMic.