I never have my hard drive on the desktop. 
I don't want it there, for a neat appearance 

 but I have Hard Disks turned off, and the system does that by default now, I think
To turn that on - Go to the Finder menu, then Preferences. General tab, make sure that Hard disks box is checked.
(If you don't see a Finder menu, click once on the desktop background, or any folder/file)