After the paddle appears, use the W key/up arrow to move up and the S key/down arrow to move down. Press space to launch the ball forward and upward, and use the paddle to prevent it from hitting the red line. If that happens, you must wait 5 seconds before relaunching it. After 5 seconds, bricks will appear, and you can break them using a tennis ball or a small ball. The bricks will start fast and slow down as they reach the red line.
The ball velocity idea came from Warfame's Brick Breaker game: https://scratch.mit.edu/projects/572115838/. I am struggling to make the ball bounce off the bricks (and am also having issues with the small ball bounces) and am trying to fix it (I appreciate any helpful ideas in the comments). Click the button in the top-right to show/hide FPS (updates every second while the project is active).