Python script at startup

Hello, my question is, how can I integrate a .py script at boot startup?

I'm really newbie and I don't know about programming..

Thanks 😃

Just see at forum that there's auto-startup file named S99custom

I created that file: /recalbox/share/system/custom.sh

now, how can I put a python script located on:
/recalbox/share/system/script.py

on that custom.sh?
Thanks for the reply.