I'm with Palvati on this one - very possible the new drive just is not formatted yet.
Another way to get to Disk Management if you don't have a My Computer shortcut (like me) is go to Control panel, open Administrative tools, open Computer management, and finally open Storage and Disk Management.
It will take a little time - maybe 10 secs to detect all your drives and partitions, but it should display all physical and logical storage devices you have in your system with nice bars and such.
You have to see if both your 1TB drives are displayed and if both have a file system associated with them. If one does not right click it and select to format.
If in any doubt, take a screenshot and post it here before you format anything.
Here's a screenshot of what it my Laptop's Storage looks like:
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