At London 2012, 3 countries allowed women to compete at the Olympics for the first time. These were Saudi Arabia, Qatar and Brunei.
1900 1900
The 1900 games in Paris.
I don't know that history has recorded the first woman to compete in the Olympics. History has recorded that the first woman to win a gold medal was Charlotte Cooper of Great Britain who won gold in ladies singles tennis in the 1900 Olympics in Paris. The 1900 Olympics were the second Olympics of the modern era and the first that women were allowed to compete in. Women were not allowed to compete in the first modern Olympics held in Greece in 1896.
Women were first allowed in the track and field and that was the only sport they were allowed to do but now they can compete in all sports that are in the olympics.
1992 Dream team
because they liked to poo too much
Three Day Eventing was first introduced to the Olympics in 1912, with women being allowed to compete in 1952 - note that the Equestrian events are the only ones where women are allowed to compete against men on equal terms
At the first Olympics in 1896.
1900 was the first Olympics when women were allowed to compete in golf, tennis, and croquet.
Women were officially first allowed to compete in Olympic sports in the Second Olympiad, held in 1900 in Paris, France.
At the first Olympics, women were not allowed to participate. The games were dedicated to Zeus, and were therefore meant for men. Now, women certainly do participate in the Olympics.