I have a "groupon" for them how do I use it?

I did not use Groupon b/c I wanted covered parking and it was pretty cheap without it. Groupon does not allow for covered parking

Show it to them upon exiting the car

Go online on their website and reserved parking when you get to the pay screen you would put your coupon code in there to get your discount.

At the exit gate. Just park your car and go on your trip.

You show it to them as you exit at the gate, when you pick up your car!