Just as you did in Lesson 2, you're going to bring photos into iPhoto. And as you did there, you'll add folders of photos as if they were rolls. (Before, however, you were simulating importing rolls from a digital camera.)
Drag the Petroglyph Stills folder of photos from the desktop to iPhoto's Source list.
You can import a folder by dropping it in the main window, but you might as well take it right to the Source listthis simultaneously creates an album for you, with the name of the folder (Petroglyph Stills), and loads all the photos into it (as well as into the library).
Now all the stills from the video are in iPhoto, in an album and ready for you to organize.
Open the Petroglyph Stills folder.
Rearrange the photos to your liking.
As with editing video, they don't need to be in the order in which you shot themand in fact, they probably shouldn't be.