Some questions about my first use lvgl

I have a lot of questions about LVGL, such as API usage, and this has so much of a learning cost that novices can’t learn how to use it in a short period of time. There are also some controls that are mentioned in the documentation, but not in the source code, like page, cont, do I have to implement it myself?

LVGL have many examples and demos. It enough to learn

All widgets from documentation is present by source code.