This is when you are a kid, after you have met the princess and been told to go to the death mountain, at that time your fairy will say to meet saria.
When you reach to kokiri forest, talk to mido and he will say to go to the lost woods.
The highest place in the kokiri forest is the lost woods.when you will go in there you will need to go to the right way otherwise you will never pass the lost woods.
The way:
RIGHT,LEFT,RIGHT,LEFT,STRAIGHT,RIGHT