Regular or Goofy?
There are two possible ways of standing on a snowboard. If you are going to snowboard with your left foot forward then you will be snowboarding in what is termed the regular position. If you snowboard with your right foot forward then you are goofy (or at least, that is the name given to your position.
If in doubt you can try the following test in the comfort of your own kitchen:
Run towards your kitchen and skid across the linoleum floor. Observe which foot goes forward. Put that foot forward on your snowboard. This test can also be administered hillside by directing the student to the nearest icy sidewalk.
Beware of other tests (shoving, jumping, kicking, baseball batting, cartwheels, etc.) and note that this has nothing to do with being left or right handed. The kitchen test is one that directly tests your preferred stance in a balance sport (if you windsurf, waterski or skateboard you will already know your preferred stance).
If you are still in doubt when hiring your board, ensure that you get a symetrical board whereby the bindings may easily be rotated from goody to regular (and vice versa) by your snowboard monitor. (Note that some bindings may rotate, but if they have an "incline" then this also needs to be reversible).