Creating a New Partition
1. Open the New Partition wizard by right-clicking in an area of free space on the external hard drive at the bottom of the Disk Management window, then clicking "New Partition."
2. Skip the "Welcome to the New Partition Wizard" window by clicking "Next."
3. Select the type of partition you want to create in the "Select Partition Type" window. If your external hard drive has three or fewer partitions on it, just click "Primary Partition," then click "Next."
Primary Partitions vs. Extended Partitions vs. Logical Drives: Hard drives support up to four primary partitions, and every partition after that must be a logical drive in an extended partition. However, an extended partition must be created in place of one of the four primary partitions for this to be the case. So, if you want five or more partitions on your external hard drive, first create an "Extended Partition," then go back through the wizard and create additional "Logical Drives."
4. Type the desired size of your partition into the "Partition Size in MB" box in the "Specify Partition Size" window, then click "Next." The size of the partition must be equal to or less than the "Maximum Disk Space in MB" value. If you only plan on creating this one partition, make the partition as big as possible, equal to the "Maximum Disk Space in MB" value.
5. Assign a drive letter to the partition in the "Assign Drive Letter or Path" window by clicking the box next to "Assign the Following Drive Letter," then click "Next."
6. Format the external hard drive's new partition in the "Format Partition" window. Type a name for your partition into the "Label" box, then click "Next."
NTFS vs. FAT32: You should leave the default file system as "NTFS." NTFS is a more modern file system than FAT32 and has many advantages. While compatibility with Linux was, in the past, a reason to choose FAT32 over NTFS, newer Linux distributions contain full, out-of-the-box support for writing to NTFS drives.
7. Verify the settings of your new external hard drive partition in the "Completing the New Partition Wizard" window, then create the new partition by clicking "Finish."
See Microsoft's Support website for more information on using the Disk Management tool.
Image Credit: Wikimedia Commons/Qurren