All animations you create and save are stored in the library, categorized into folder by the page where they were created.
On the right side of an animation, you can see and control if the animation is hidden (so it doesn't load on the frontend, but is available in the library) or global (so it loads on all pages).
Edit the animation by clicking it, or access more options using the right-click.
Other lessons:
Lesson 1: Getting started with motion.page
Lesson 2: How to use motion.page to create your first animation