On either side of your spacebar is a keyboard button named the "Windows Key". It should be beside your ALT buttons, and will have the Microsoft Windows flag icon as its label.
If you hold the (Windows button) and poke "D" on your keyboard, your PC will switch to your desktop immediately by minimizing all of your open Windows.
You would use (Windows button)-D to access My Computer or Recycle Bin or any folder on your desktop. You can also use (Windows button)-D for privacy: quickly hide all your windows when someone approaches your desk.
To restore any of your minimized windows, simply click the Taskbutton of the desired window (Taskbuttons are the shrunken windows inside the Taskbar at bottom of screen). Alternatively, you can use the ALT-Tab keystroke to switch back to any minimized windows.
Give (Windows button)-D a try. It is a favorite keystroke amongst regular users of Microsoft Windows.