The "easy and dirt" way to auto fire is add an invisible turret on top of it.
The AAI "movement" are done by invisible bitter that "guides" the car.

but i have no clue how i code this.

You may get some help form "Earendel", he made the AAI mods
There are something here about, but not sure.
https://forums.factorio.com/viewtopic.php?f=25&t=34439

makes me think of ingame mechanics that you stick weapons in it to 'arm' it and if wanting it to auto fire you stick a construction bot to 'man' it ,reminds me of my hoppe somone make a good mood ading flak guns & flying fortress bomber play for mp games.