How to divorce a spouse, residing in foriegn country, who cannot be located

You'll need to file your divorce complaint, first, and then make a motion to the court, with what's called an "affidavit of diligent inquiry" that says you've really tried to find him (explaining how), and that you can't find him, and asking for permission to serve him by publishing a notice in the newspaper for whatever county you're in.  See New Jersey Court Rule 4:4-5, for the details.

Why is this allowed?  The newspaper publication is considered "notice to the world," but this is a good example of what's meant by a "legal fiction," since the chances of your husband seeing that notice, in time to respond, are microscopic.  It's allowed for just your situation:  so that you aren't trapped in a marriage to a man who's disappeared.