You already created some graphic symbols when you worked with the drawing tools in Lesson 2. Graphic symbols are useful when you have static graphics or bitmaps in the library and want to use them throughout your Flash document (and particularly when you want to reuse the images). Static graphics refers to graphics that are just going to sit around dressing the Timeline up a bit without having any kind of "nested" animations of their own. Graphic symbols can't be controlled with ActionScript, so they can't take instance names.
You can create animations inside of graphic symbols, but here's something to be aware of: The animation inside the graphic symbol will play only if the Timeline the graphic symbol is in is playing. Think of graphic symbols like kids holding hands with their parents. If the parent stops, so does the child, even though the child is its own self-contained identity. When the parent moves, the child moves with the parent. This can be useful in very limited circumstances, so by convention, nested animations (animations inside of symbols and not on the main document Timeline) tend to be reserved for movie clips because they are totally independent of their parents (like teenagers!).
You cannot apply filters to graphic symbols.
When you have a graphic symbol instance on the Stage selected, you can change its Properties in the Property inspector. The Instance Behavior drop-down list allows you to change that one instance of the symbol so that it can behave like a button or a movie clip. The Swap button lets you switch it out with any other symbol in your library. Options for Graphics is used to control (to some degree) any animation that the graphic symbol might contain in its own Timeline. You can tell it to Loop continuously while the parent Timeline is animating, Play Once only, or display only a Single Frame. The Color menu is used for instance effects and it contains options for altering brightness, tint, alpha (opacity), or a combination of those things in the advanced option. You will look more at the properties of graphic symbols in Lesson 5 on animation.