Import Fireworks PNG files into Flash as flattened images or as editable objects. When you import a PNG file as a flattened image, the entire file (including any vector artwork) is rasterized, or converted to a bitmap image. When you import a PNG file as editable objects, vector artwork in the file is preserved in vector format. Choose to preserve placed bitmaps, text, filters (called effects in FireWorks) and guides in the PNG file when you import it as editable objects.
For a video tutorial about the Flash and Fireworks workflow, see www.adobe.com/go/vid0194.