Hey there, paintboy131!
First, make sure you have activated the SATA port you connected your drive to in the BIOS.
While in disk management, you need to right-click on the drive where it says 'unallocated' and create a partition and format it with NTFS. You can also use the links that @Ace251091 mentioned.
If you don't have such an option in Disk management, you most probably have to initialize the HDD first.
Here are a couple of step-by-steps that might be useful as well
How to initialize an SSD/HDD on Windows:
http://wdc.custhelp.com/app/answers/detail/a_id/1018
How to partition and format a hard drive on Windows:
http://wdc.custhelp.com/app/answers/detail/a_id/3865
Hope this helped! Good luck!

SuperSoph_WD