Drag and Drop what you want to add. Remember the WD My Cloud is just another computer with some extras that come with it.
See my post in this discussion/topic; http://community.wd.com/t5/WD-My-Cloud/uploading-music-from-Itunes-to-mycloud/m-p/797967#M21621, You don’t have to move all of them, only the ones you want to move.
Posted by,
cat0w (USA)