You can move files from iPhone/iPad apps to iBridge/iAccess if the source app supports Open In. The file you copied will appear in the "Inbox" folder of iBRIDGE/IACCESS STORAGE. In order to find it, go to Leef app => File Manager =>iBRIDGE Storage => Inbox.
Note: Apple forbids copying/moving files bought from iTunes to other apps or external drives. For that reason, you cannot move music from "Music" app and movies from "Videos" app to iBridge using your iPhone. The simplest way to move music is to use your PC and iTunes.
Launch iTunes on PC, plug in iBridge, choose music (albums, songs), movies (non DRM protected) you want to transfer and drag and drop them to iBridge.
Note: There are apps with protected content that would not allow you to move content out of them. The examples are Amazon app, Vudu app, etc.