Step 2: Formating
Open the application "Disk Utility" (it's under the utilities tab in your applications folder. Picture 1)
With disk utility open, select your hard drive model; not the name you've given it, just the model...
Then, select the partition tab... Picture 2
Now, you should see a drop down menu labeled "Volume Scheme."
This menu is were you choose how many partitions you want on you hard drive.
My drive is pretty big so I chose three partitions..
Chose your desired size of your partition.
Then, in the drop down menu labeled "Format" select "MS-DOS (FAT)" for your 360's partition;
you can choose different formats for other partitions.