I'll preface this by saying I've already searched Google and since I'm fairly incompetent when it comes to technology, most of the information I found went way over my head and trying to understand it gave me a headache.

So the dilemma: I purchased an external hard drive around 6 years ago to upload a bunch of movies and tv shows to take with me on a 6 month overseas trip (let's not get into the morals of this.. I know). Since then, I have added all my pictures from my time overseas, college documents, engagement pictures, wedding pictures and multiple iPhone back-ups of my pictures etc.

I have always had laptops / computers that are PC's until last year when I bought a Macbook Air. My family has been iPhone / iPad users and have loved the Apple sharing abilities between them, so I figured I would give the laptop a shot too.

Last night I was attempting to back up the Mr.'s photos on his phone to my hard drive and to my surprise my external hard drive does not play nice with my Macbook (I really should have expected this. I know better.)

Now my question is this: What is the best way to reformat the hard drive without losing all of the content. Is this possible? If not, what are recommendations for external hard drives that do play nice with the Mac OS? And if I do purchase a new one, how do I transfer the files from one to the other?

TL;DR - I need guidance from more intelligent people who can tell me if 1) I need to reformat my hard drive to work with my Macbook or if 2) I need to buy a new one, and 3) how to go about transferring the files currently on it to avoid losing them in the process.