It is really difficult to ask general “how do I do this?” question.
You can read more on the subject here:
Now to get back at your project, I would advise, as @tony said, to divide your project in different objectives, master them and at the end put everything together. It could be something like this in your case:
- Draw an ellipse where you want, the size you want
- Change the color of that ellipse
- Move it over time (no matter how)
- Change the size over time (no matter how)
- Change the color over time (no matter how)
- Now control how the ellipse changes over time (position, size and color)
- How to draw multiple of them (which data structure adopt for the project)
- Enjoy
Now if when trying to break it down you run into problems, come back and post your code here. Explain what you want to achieve and what exactly is the problem that you encounter. We’ll all be happy to help