I think this is what you need to do.
Changing where your iTunes files are stored
By default, songs and other files you import into iTunes are placed here:
My Documents/My Music/iTunes/iTunes Media
To change the default location of imported files:
Choose Edit > Preferences and click Advanced.
Click Change and select a new location for your files.
From now on, new songs and other items you import will be stored in the new location. Songs you've already imported stay in their current location.
To restore the iTunes Media folder as the default storage location, click Reset (in the Advanced pane of iTunes preferences).