Initial Setup of External Hard Drive for iTunes

I am trying to move my music off of my MacBook's HD and onto an external drive in order to free up space, but I can't figure out how to get iTunes to recognize the music on the external drive correctly. Every time I try something new like importing or adding, iTunes adds the music to the library on the HD. Is there some way to get iTunes to simply read the music off of the external HD without loading it onto the MacBook?