Do you want it saved within a session or saved so it can be recalled even if the game is closed and reopened?
Within a session is simply storing the point
as a variable. If you want to save more than one then just create an array and .push each new point into the array when you want a 'save'.
If you want it saved
saved you should look into shared objects
. They are fairly simple and are a must-have for most actual flash games.