They are saved to your unit, and it's not a good idea to try to save them to a mapping card. I always keep my mapping card write protection tab so I don't accidentally write anything to the card.
I'm sure if you do a search on here for export humminbird nav data, or a google search, you will get a lot of information and probably even some youtube videos of how to do it.
Humminbird PC also has help files built into the program.