Its very simple floof here is how to downlaod a map.
This video had very many likes and is said to be a easy watch and learn. :)
http://www.youtube.com/watch?feature=player_detailpage&v=vI7dtnqtsDw (http://www.youtube.com/watch?feature=player_detailpage&v=vI7dtnqtsDw)
Yeah, the video that Tokoa sent is right.
Basically, you just click the download link to the map you want to download, then click 'download' and wait till it's done.
Afterwards, to install it, you just need to open the folder you downloaded and drag all files into FeralHeart > Exports.
Then you will have to restart FeralHeart and will be able to find a new portal to the map you downloaded in Cape Of Distant Worlds.