If you want to launch applications from locations other than your Applications Folder, you will need to create an Alias (or Shortcut). An Alias is a link to the selected application in it's original location.

Follow these steps to create an Alias:

1. Go to your Applications Folder and select the application you want to access from your Desktop.
   
    
2. Right Click (Command + Click) on the Application icon and select Make Alias.
   
    
3. Move the new Alias onto your Desktop.
   
    
4. You will now be able to open your selected application from your Desktop via the Alias.