ProMods

Hi guys, so basically ive never created a mod for any game ever but would like to create a custom skin for a Merc Sprinter for ETS2 and have it as a AI traffic car, ultimately would like to be able to encorporate it into a random traffic event and that could hopefully become part of the promods map expansions, or at the very least run along side it.

Where would i start and honestly is it something that i could learn to do?

TIA