video sound

Can anyone please tell me how to get the sound I have edited in Audacity, back to the original video? I have a video with really loud background noise. I copied the sound track to Audacity and used the noise removal in effects. Now I would like to copy this edited sound track back to the video.

Audacity doesn’t record video, so the only option is to use the split tools in almost any video editor.

Thanks I will try that, I use iMovie so I will look for the split editor in there.