The Still Images section
This section of the Album displays thumbnail icons of image files, which may include grabbed video frames, photographs and bitmapped drawings. Most standard image file formats are supported. As with video scenes, images that are in use in your current movie are indicated by a checkmark symbol.
The Still Images folder: The icons in the Still Images section represent files in the folder named at the top left of the section. Images can be added to the section by storing them in this folder. For instance, you can save grabbed video frames into the folder from the Frame grabber tool, copy images using the Import Wizard, or save your digital photos from a desktop photo-editing application. You can also select a different folder to be the source of the section.
Click here for information on using still images in your movie.