Transferring music from external hd

Seemed so simple at the Apple store when a genius showed me, but I cannot remember for the life of me now.

How do I transfer music from my external hd back on to the hd on my computer keeping all the tags? I'm trying to put my songs just back in itunes and not in any software program. Whenever I try to transfer it the music/songs transfer fine, but I want the # of plays to show up and my old playlists to copy too. As I understand it this info is in some kinda tags. I recently just did a clean install of snow leopard.

Like I said earlier, the guy at the Apple Store made it happen easily with tags so as to show the # of previous plays from my external hd, but I am really stumped. I'd love to just go have him show me again but I live 3 hrs away.