Not sure where you tried to drag it from..... but, first of all, by default, the Macintosh HD icon is in the top right (not left) corner. And, the desktop IS the Finder. Try this first:
Go To Finder -> Preferences -> General - make sure the "hard disks" are checked under "show these items on the desktop".
Also, navigate to: Users -> Library -> Preferences -> and delete the following: com.apple.Finder.plist.
After that, Restart.
See if it shows up in its default spot now. And, as a general precaution, it is best not to move or otherwise "play with" the Macintosh HD. That is your hard drive and system - in other words, everything that makes your Mac run. There are far easier ways to access the contents of it, such as putting Applications, folders, etc. for easy one-click access into the dock. I never open or otherwise use that HD icon - I access everything via the dock.
