Turn the watch so that the crown is at 3 o'clock.
Following the line of the pusher stem at 4 o'clock, there is a small hole with 'push' and an arrow next to it (the hole in the grey plastic). With the crown in the first position, depress the button inside this hole (use tip of tweezers) and pull on the stem.
If that doesn't work, look between the crown and the pusher at 4 o'clock, see if there is a small lever with a hole/indent on one end, which should move in and out as you pull/push in the crown - whatever crown position moves the lever out is the one you need - push down on the hole/indent end of the lever and pull on the crown.