(2) New Document. Canvas size doesn't matter, resolution 96 pixels per inch. Canvas color transparent.
(3) Find an image to work with. Open http://google.com. Click IMAGES, right about the search textbox. Type the name of what you want to search for.
(4) When you find a picture you'd like to work with, right click it, choose copy. Switch back to Fireworks. Edit>Paste.
(5) Switch to Preview mode.
(6) In the Optimize panel (far right side of Fireworks), switch to GIF and reduce the colors to 4.
(7) You can't copy & paste this one the same as everything else. File>Export; use Posterize as your filename.
(8) How to get this posterized picture into PowerPoint: In PowerPoint select Insert>Picture>From File
Here's a well known example of Posterize.
