First of all, why would you have Olaf with the marksman, who I'm assuming is in bottom lane?
Secondly, diving (which is what I think you meant when you said "diver") the adc should only happen if you plan to kill them, otherwise you should avoid turret shots as much as possible. The point of a dive is to execute an enemy on presumably low health. Damaging them and taking minion + turret damage is not an effective strategy, and is not considered "diving", but rather taking free unnecessary damage. Don't be stupid.
Zoning an enemy has to do with** presence. If you will surely win a trade with your opponent, you have kill potential. If you can, harass them without taking damage if they try to take a minion. If they're low enough, and you have kill potential if they try to farm more, they are forced to avoid farming. Zoning is to deny farm with presence**. If they can't take minions, they don't earn as much gold. Without gold, they cannot get items.
It is much easier to zone a melee opponent with a ranged poke champion (
vs
) but if you're Olaf and you're vs a ranged AD carry, zoning is a bit harder because of their superior poke and range.
A good example of being able to zone is
. He has huge kill/pick potential with his rocket grab, so just with his being there, he can zone enemies from farming.