Bouncing object!

Hello ! I wanted to make a game and I wanted to create a box and some circles inside it ! At beginning i would like the circles to move at random direction with random force for infinite time! And if they hit the wall they will bounce off the wall and towards another wall (random or not doesnot matter but should not be bouncing back and forth in the same path) !
How do I do it?

Hmm, so you have to know a bit about collisions which you can find here: Handling collisions in your game [GDevelop wiki]

To add random forces to the circles, I have already addressed something similar. You can find that here: How do I create a random angle for a force?

Combine them together and you can achieve what you want.

For collisions, make sure the hitboxes are correct for the circle.
To make the box, use line sprites so that each of the line objects can have a collision hitbox and the circle can move inside the box.