Hi, I am using Stm32f103 and I want to learn how to use Low layer API, is there a user manual where examples are built step by step??

[EGarc.3]

What are your recommendations for learning to code and configure peripherals and also learn the architecture of the Microcontroller??

[TDK]

The reference manual is the best place to learn the architecture of the system.

https://www.st.com/resource/en/reference_manual/cd00171190-stm32f101xx-stm32f102xx-stm32f103xx-stm32f105xx-and-stm32f107xx-advanced-armbased-32bit-mcus-stmicroelectronics.pdf

The LL has a user manual:

https://www.st.com/resource/en/user_manual/dm00105879-description-of-stm32f4-hal-and-ll-drivers-stmicroelectronics.pdf

I think it would be more useful to just generate projects using STM32CubeMX and examine the generated code to learn how things are configured using the LL library.