An Ozi "map" file is a text file that contains geo-referencing data for an associated "image" file (the map image). Ozi works with a range of map image formats so a bit more info on the format of the "image" file you want to convert would be helpful.
I strongly suggest that you head over to the
GPS Australia forums have a search around and if you can't find an answer then join up and ask. Friendly crowd and always willing to help so I'm sure someone over there should be able to help you.
Cheers,
Michael.
One foot in front of the other.