I want to draw a bouncing ball
This seems to be asking for help and advice rather than an art discussion.
The manual has a section explaining animation if it’s an animation you want to do:
Later in that section is an example of creating a simple walk cycle . Making a bouncing ball animation uses the same animation principles.
Also, a YouTube search for “krita bouncing ball” will show many tutorial videos for that.
Welcome, @Raelyn.
Do you already know how to use Krita? If so, you might follow an animation tutorial on YouTube.
(By the way, I moved your question into one of the support categories. Please take your time to choose the category before posting.)