Im stuck on this tutorial thats on YT -> Programming with ActionScript 3 - Lesson 3 pt 1 - Functions and Events

The author used premade animation with shape tween, since im learning everything from the basics i didnt know what a shape tween was but i went online and quickly learned how to make one.

When i try to use the animation.stop(); i need to define the "animation" class and the problem is that i dont know how or what to convert, when i try to convert my square to a symbol i lose the whole shape tween animation and frames get all dotted in the timeline, i have no idea what im doing wrong.

In the 39s of the video the author checks the animation and has a nice green line of frames on timeline then he clicks on Scene 1 and on the timeline it vanishes and focuses on single frame, this part i dont understand either. Its like he has that whole animation in 1 frame converted as a symbol and then he can apply code to it like animation.stop(); ?
IF i understood this correctly then how do i convert the whole animation like that ? Hope anything that i wrote makes sense and anyone can explain it to me cuz im rly stuck on this =(