My trusty 2009 MacBook is on its last legs, and so I am transitioning to a MacBook Air. I have my Lightroom CD (version 3) but no longer have a CD port. I have tried Adobe Chat at calling Customer Service, but to no avail, being directed both times to post for help here. How can I get Lightroom on my MacBook Air? I am not asking for the latest version, just looking to use what I know.