After you exported it, you need to take the files that you used in the map, and put them in a folder or a winRAR. Once you upload that to Mediafire, people can download it.
You would need in the folder;
The .fhm file (Feralheart map)
The .fho files (Feralheart objects. So whatever meshes you used in the map)
The .fhw and .fhs if you used either weather or sky.