New internal hard drives are supplied with no partitions on them, so that means the drive has no drive-letter, which in turn means Windows can't show that drive in Windows Explorer.
You have to prepare the drive so that data can be written to it:
Right-click the drive's ribbon in the bottom-right panel in Disk Management, and choose "Create New Simple Volume". That will only take a few seconds.
Then right-click the new volume and choose "Format". Formatting a 1TB drive will take quite some time.
When that's done, re-start Windows and you should be able to see your new hard drive in Windows Explorer.