How do you sync audio to a video of someone lip-syncing?

If you are attempting to sync music audio with the video in Windows Movie Maker, it is not an easy task. Windows Movie Maker is a very basic editing program with limited features.

The best way to achieve what you are asking is to Split video/audio clips along the time-line and keep moving them until you get close to the synced effects you want. I will be the first to admit, this is no easy task.