If you've been told that you can go to greenhorn plains then go to the fighter area, talk to Beth and she'll ask what dig site you want to travel to, then give you the options and you have to click on greenhorn plains.
The term, Greenie, is derived from Greenhorn. This comes from the horns of a newly slaughtered, young animal. This is a term used to indicate someone who is new to a country. It may also refer to an environmentalist, sometimes called a "tree hugger".
The cast of Greenhorn - 2003 includes: Bettina Dorn as Daughter Kolja Kleinschmitt as Grandson Joachim Lautenbach as Soldier 1 Josef Quadflieg as Old Karl Stefan Rosmiarek as Soldier 2 Tim Williams as Sam