To (manually) add video/audio files to your iTunes library, follow these steps:
- Open iTunes
- Click small button at the upper left corner and select the "Show Menu Bar".
- Click on the "File" menu and either select:
- Add File to Library
- Add Folder to Library
In the window that opens select the file or folder and click on "Open". The file will be imported into your iTunes library:
Note that: iTunes supports the following formats:
- Audio: AAC, MP3, WAV
- Video: QuickTime or MP4.