Give the ball a starting velocity in the X direction, say 1 m/sec

Give it a starting velocity in the Y direction, if we assume it's being thrown upward, say 0.5 m/sec

Now let's assume there's no air resistance, so the ball is not going to change speed in the X direction,

i.e. X Accelleration equals zero.

But there's gravity, which is a constant downward acceleration, so each second it's going to increase in Y velocity by G m/sec,

on Earth's surface G is IIRC 9.8 meters per second.

So that shoul dbe all you need to calculate the ball's trajectory. Starting at X,Y position of say (0,0), calculate its position 0.1 second later, easily done since you know the X and Y velocities. Also calculate a new X and Y velocity, given the X and Y accelerations. Very simple math.

And Oh, when the ball hits the ground (Y = 0), it will bounce, assume a very elastic ball, so the Y velocity reflects. Very easy, very simple, as the old Chef Tell used to say,