The first Closed Beta Test started in November 2011 in Korea and lasted a few days.
The second Closed Beta Test started in October 2012 in Korea and lasted a few days too.
Open Beta Tests started in November 2012 in Korea and lasted a few weeks.
The first Free to Play server opened in Korea in December 2012.
The English Server FGT (Focus Group Test) started in December 2014.
The pre-launch site started, you can sign up for the beta there. More info here
Europe and other regions probably have to wait till 2014-15 to play the game.
Find out more: Release Date Discussion