iTunes Help!

[gubi-gubi]

Had to reinstall iTunes and stuff a month or so ago and haven't got round to sorting all my new mp3s into yet so I went to do it today and like half the files have the '!' missing sign on them. I know where they are but when I tell it where one is, the rest are still missing even though they're all in the same place. Anyone know how to tell iTunes where the rest are in one go like a group location or something?