actionscript 3 help for absolute beginner

I don't want to seem unhelpful but this is something you can search for and find quite extensive resources on it. We would just be repeating any of them or re-inventing the wheel. There's both text and video tutorials on how to make pong with AS3. The basics are going to be binding keys to paddles, moving the ball and calculating the bounce directions. A good beginner tutorial, but not really for the absolute AS3 beginner.

If you don't know anything about Flash itself (Libraries and their objects, instances, the timeline, etc) you're going to find any tutorial a bit challenging. I suggest you look over the built in docs or search for a Adobe Flash/Animate interface tutorial so you know your way around.

After you understand basic timeline, symbol, etc concepts, it's just picking a tutorial:

https://www.google.com/search?q=actionscript+3+pong+tutorial