Hello, I have been a long time PC user and I finally upgraded to a Macbook , ergo, i'm an ultra n00b with a Mac . With that said, I have been using a WD My book essential 1TB usb 3.0 and have already saved multiple files to it (200GB+). As of right now, I can only read these files on my Macbook and have no writing permissions to the external HD. How do I go about gaining access/write privileges without compromising any of the contents on the HD (I don't want to reformat/delete all that I have on the HD)? I'm worried that I may lose my data already on the HD. Ideally, I'd like to be able to plug and play this HD on my Macbook and transfer files to and from my PC. Any help would be much appreciated. Thanks!