WD My book Essentials works on my PC but won't let my Mac make any changes to it

I have saved everything from my Toshiba laptop to my WD 3TB My book essentials external hard drive. Now that computer is **bleep** (still partially usuable) and I thought that I could be able to just use my new Mac Book Pro to access and use with my My Book Essentials external hard drive, just to find out that I can see whats on the hard drive but i am unable to make any changes or add anything to it or remove anything from it or even pull pics off of it for my projects. I had entered the unlock code but i got nothing. I am having a hard time finding any info on here. What do i have to do? I still can use the other computer if i need to make some sort of change to disable something or whatever. I would really like to make my Mac Book the computer to use with it. HELP!!! 

This is a Windows/Mac issue. A drive formatted NTFS for Windows is read only on a Mac. A drive formatted on a Mac is not readable on Windows. I’m not a Mac user but see if this helps http://www.cnet.com/news/how-to-manually-enable-ntfs-read-and-write-in-os-x/ Joe