Okay, so there are 7 new Dirt Tour events that come with the Monte Carlo track pack, but you will first need to have all 4 seasons unlocked to complete them all.
Brembo Blast - Lantosque Historic Run
Rampage - La Bollene Legends
Off Road Rush - Alpine Open Cup
Gold Nixon Series - Castillon Trophy
International Skirmish - Riveria Open
Repsol Masters - Le Sevil Legends
Monster All Star Showdown - Battle in Luceram
You do not need to come first in every event, but to come first overall.
The achievement will unlock in the loading screen after winning the last Dirt Tour event.