What is Goofy and Regular?
Goofy and regular are simply terms describing which of your feet is your lead foot (the foot at the front end of the snowboard). Regular describes the stance for people who have their left foot at the front. Goofy references people who have their right foot at the front.
If I have never been snowboarding then how would I know if I am Regular or Goofy? This is quite simple. Imagine that you have an icy path ahead of you and you take a run towards it with the intention of sliding on the ice. Which foot would you naturally lead with? That mental exercise will answer the question for you.