One of the benefits of using Custellence is that you'll never have to deal with multiple versions of a map, wondering what version is the last one. In Custellence, all changes are saved automatically, as well as being logged.
How to create a version of your map
However, there might be occasions when you want to save a certain version of a map. And this is easily done, by simply making a copy of the map, and then save one of them with a different name. Just click on "make a copy" in the map menu and make sure to give the copy a different name. Then you are all set!