My music is on an external drive. How do I change computers?

I am currently Rekordbox using a 2010 model Macbook Air (El Capitan).  I have all my music files on an external HD.  I want to switch to a different Macbook Air (newer model) and want to use my external HD with the new Macbook Air.  I don't want to lose all the playlists that I've created.  How do I transfer the playlists to my new Macbook Air?  Thanks for any info and sorry if this is a duplicate question.