here’s what I have so far: https://scratch.mit.edu/projects/1383891195

You don't have any touching (sensing) blocks.

For bouncing off top and bottom edge of screen you need to reverse the Y flow/movement of the ball.

You'll need a way for the player paddle to reverse the X flow/movement of the ball.

NMario84 wrote:

You don't have any touching (sensing) blocks.

For bouncing off top and bottom edge of screen you need to reverse the Y flow/movement of the ball.

You'll need a way for the player paddle to reverse the X flow/movement of the ball.

I get that, but I don’t know how to define the movement/momentum of the ball in order to reverse it.

move (X) steps // Replace X with any number for the ball speed

if on edge, bounce // Checks if the object hits the edge of the screen to reverse direction.

I just did a search myself, and here's a few youtube tutorials I saw that may help:
https://www.youtube.com/watch?v=QQhGdzySZ-o

https://www.youtube.com/watch?v=sn6Q1GVBdKs

https://www.youtube.com/watch?v=JfFzKQnlZAM

I made a remix of your project that uses individual sprites instead of clones and has some movement code in it. https://scratch.mit.edu/projects/1384364401/

Clones are okay but sometimes they get in the way of experimenting and making things.