How to create a theme in code in phpBB?

Question

phpBB

I need to implement an actual parser for phpBB with the placement of topics and comments on them.
I will take the data from a third-party API, I would like to see the code itself for creating topics. Perhaps there is already a ready-made extension that I would redo.
Or you can just directly create records in the database, or is it not comme il faut?
And where can I read how to interact with phpBB?

Answer 1

https://wiki.phpbb.com/Function.submit_post