Adding media files to your iTunes library is a great way to keep your collection organised. The iTunes program maintains and indexes your media, so you don't have to. Instead of keeping tabs on a number of media files and folders on your hard drive, let iTunes act as a hub. iTunes makes transferring music from external hard drives, CDs and flash drives easy with its convenient "Add to library" feature.
Insert your flash drive into a USB port on your computer.
Exit out of the Windows Removable Device dialogue box, if it appears.
Open your iTunes preferences from the menu bar. Click the "Advanced" tab. Check the box beside "Copy files to iTunes media folder when adding to library" if it isn't already checked. Then, click "OK" to save your changes and exit the dialogue box.
Select "File" from the menu bar, then click "Add to library." A browse window will appear. Locate your USB device and click on it to view its contents. Select the music file(s) you want to add to iTunes.
Click "Choose" to close the window. iTunes will add the files to your library. Repeat this process if you want to add more files or folders.