How to partition My Passport for Mac


I recently installed a 1 TB My Passport for Mac to back up my MacBook Air using Time Machine - Format Mac OS Extended (Journaled). It is working just fine.

I want to partition My passport to a 300 GHz and 700 GHz. The 300 GHz for backing up my computer using Time Machine. The 700 GHz partition I want to use to store my movies and music. This way when the 300 GHz is full the system will automatically delete old back up and I have my 700 GHz available to save other files. 

How do I do that? Thanks for the help.


From the disk utility select the option to create two partitions instead of one, it will then give you the option to select the size for each partition.