Hard drives in Seagate's FreeAgent line -- except for the Go Pro for Mac and the Go for Mac -- ship with NTFS, a file system designed for Windows. Your MacBook can not read or write to a NTFS drive, so you will need to reformat it to a Mac-compatible file system. Formatting a drive will erase all its contents, so back up the drive first if you've already copied files to it on another computer.

Step 1

Connect the FreeAgent to any open USB port on your MacBook.

Step 2

Open the Apple menu and click "Go" and then "Utilities." Double-click "Disk Utility."

Step 3

Select the FreeAgent drive and open the Partition tab. Open the "Volume Scheme" drop-down menu and change the setting from "Current" to "1 Partition."

Step 4

Click "Options," select "GUID Partition Table" and press "OK."

Step 5

Change the "Format" setting to "Mac OS Extended." Optionally, type a name for your disk in the "Name" text box.

Step 6

Click "Apply" and then "Partition" to confirm that you want to erase the drive and reformat it. If Time Machine appears after the format, click "Cancel" unless you want to use the drive for system backups.