The key located on your keyboard between the CTRL key and ALT key is known as the "Windows" key.  It looks like a window swooshing through the air.  This key is very instrumental in the using shortcuts functions.  Make sure to hold this key down while pressing the letter noted below.  Some of the most common are:

Window Key + D - minimzes all windows and takes you to the Desktop.

Window Key + E - opens <Window Explorer>.

Window Key + F - opens the <Search> function for Files and Folders.

Window Key + R - opens the <Run> Command.