You'll find detailed information on the vehicle page in Tankopedia.
How the position in the rating was determined?
To get on the leaderboard, you were to choose a vehicle that could participate in the event and play at least five battles on it. Your position was determined by the amount of base XP you earned using this vehicle over a series of 5 battles: the greater this value were, the higher your leaderboard position would be. You could use multiple vehicles to place on the leaderboard multiple times.