iTunes OSX: Add external HD library without it moving into music folder

Hey guys,

Just got my first Mac (Mac Air yay), anyway, one thing that is annoying me is I am trying to add my music on my external HD to my iTunes library. However every time I do this, it copies my library from my external to the music folder on the laptop.

Is there a way to prevent this from occuring?

The external harddrive is a Seagate, and it is in NTFS format, however I have installed the Seagate NTFS Driver, and therefore the external HD is writable.