FOTA using SIM Modules

Hello all,
I am learning to implement FOTA. I am currently using SIM7000 connected to STM32 via UART. I also have ESP8266 connected via UART, so FOTA via any method seems fine.

I guess this will need me to make changes to my schematics as well as firmware.

What are the steps to carry on FOTA? What all changes need to be made on schematics and what all in firmware?

Thank you in advance.