How to create a quest with a region.

function ObjectiveComplete(hero)
if hero=="your hero's name" then
SetObjectiveState("Scripted quest name", OBJECTIVE_COMPLETED, PLAYER_Player number)
end
end;

Trigger(REGION_ENTER_AND_STOP_TRIGGER, "Region name", "ObjectiveComplete")

Please ask similar small questions in the appropriate topics: Scripts and Current questions and answers about the map editor, so as not to create new topics)