To share a map you must load your map in Map Maker and hit the Export button.
Go to your "exports" folder and files such as .fhm (map file), .fho (object groups), .fhw (weather cycle) and .fhs (sky file) that were used in your map will appear there.
Gather them together and place them in a new folder, compress it and upload the folder on a file sharing site such as Mediafire for example.
Give your friends the download link and then they must place the files into their "exports" folder, the portal will be found in Cape of Distant Worlds.
Try this tutorial for the black screen..
http://feral-heart.com/index.php?option=com_jfusion&Itemid=2&jfile=index.php&topic=13593.0
