This is one of the first things I have learned when I switched to Mac, and I thought it may be handy to any new Mac users out there.
Sometimes you would like to save the file to your Desktop. Once you click on File | Save as in your application menu bar, the save dialog box appears offering you one location, usually the Documents folder.
Of course you have a few options what to do, you can save it there, you can click on the drop-down menu and select one of the most common locations, or you can click on a little triangle icon and open the Finder mode.
But if all you want is to save the file on your desktop, simply hit Command-D (Apple-D) on your keyboard, and the save location will automatically change to Desktop.