Change Music Libary link to external hard drive

I changed my music libary to an external hard drive via iTunes/Preferences/iTunes Media Folder location/Change. I then deleted the files / folders from my hard drive. Now it says it cannot locate songs (and shows and exclamation mark to the left of the song and a cloud to the right). Can somone please advise how I can properly reference my iTunes to directly link to the external hard drive folder?

Thanks,

Brett