Step 1. Connect iPhone to Computer.
The starting image of the software is just like below. When you have connected iPhone to computer, the software will show the detailed information of the iPhone. The library and playlists of iPhone will show in the left sidebar accompanied with the library and playlists of iTunes.
Step 2. Add files from computer.
Users have 4 ways to add files from computer: the first one is dragging and dropping the files directly into the software window; the second way is to click the Add button at the top middle of software; the third way to is click File > Add > Add File/Add Folder at the upper right corner; the fourth way is to right-click the name of the library and choose Add File or Add Folder.
Step 3. After adding files to the software, the transfer begins.
A dialog of transfer process will show up. This dialog shows you the percentage of the transfer, and the names and numbers of the files being transferred will also be shown. When the transfer is ongoing, please don't disconnect the iOS devices.