Moving around things that never change is fine, but if you want to animate a bird or even a person walking, you need that thing to move its parts as well as move across the screen.
Here is a video showing all the steps below.
To do this create a movie symbol with Insert > New Symbol
When the dialog box opens, name the symbol and choose Movie Clip as the type. Then click OK.
Don't Panic!!! When everything in your timeline is gone. This is supposed to happen. :)
You are now working on a movie clip that will go into your animation later. To get back to your animation, click the little arrow.
If you clicked the arrow, you need to now go to the Library to get back to the bird. Click the tab and double-click the bird symbol.
When you are in the bird symbol (or whatever symbol you created), draw your bird with the brush tool. Don't worry about a lot of detail, the bird is going to be in the distance.
Right-click frame 5 in the timeline and Insert keyframe. This creates a keyframe in frame 5. Erase or redraw with the paint brush so the wings move a little.
Insert Keyframe at frame 10 and redraw so the wings are down.
Insert a keyframe in frame 15 and redraw.
Insert a keyframe in frame 20 and don't do anything. The symbol will cycle back to frame one automatically.
Go back to the scene by clicking the little arrow next to where it says Scene 1, add a new layer, name it bird, and drag the bird symbol out of the library and onto the stage.
Animate the bird so it moves across the sky.
You will notice that the birds wings do not flap. :( Symbols do not animate until you test the movie.
So save your file as farleyt83_bird_001.fla and then Control > Test to see your bird flapping its wings in your animation.
File > Export > Export Video and bring your video into Final Cut to finish it with a title, a soundtrack, and credits at the end.