It is likely your iTunes Music Library will be made up of .MP3 files and .AAC files. You will need to locate and select the files in the Zipcloud app Manual Selection, below are the default file paths of where iTunes stores music files on your hard drive:
Mac OS X: /Users/username/Music/iTunes/
Windows XP: C:\Documents and Settings\username\My Documents\My Music\iTunes\
Windows Vista: C:\Users\username\Music\iTunes\
Windows 7: C:\Users\username\My Music\iTunes\
If you find some of your music has not been backed up it would be worth going to the Album in iTunes and right clicking on a track and selecting 'Get Info' it will bring up a new window and under 'Summary' you will see the file path. You may find some of your music resides in odd locations on your computer, before going through every album it would be best to follow the process below...
Locating and consolidating your media will make sure all of your content from iTunes is in the same location and is therefore organized and easier to ensure it is all backed up:
1. Open iTunes Preferences:
Mac: Choose iTunes > Preferences.
Windows: Choose Edit > Preferences.
2. Click Advanced and note the location of your iTunes Media folder.
3. Be sure there's a check in the checkbox next to "Copy files to iTunes Media folder when adding to library."
4. Click OK.
5. An alert may appear stating: "Consolidating your library will copy all of your music into the iTunes Media folder. This cannot be undone."
Consolidating will cause iTunes to copy all of your music files that appear in iTunes to one central location on your computer (the iTunes Media folder). The original files will now be duplicates which you will need to manually remove from their various locations if you don't want them to take up additional drive space.
So once your music library is consolidated you can simply select the iTunes music folder in Zipcloud Manual Selection and it will be backed up.