If you are not lucky enough to find a parking spot in the convention center underground parking lot take advantage of the free shuttle service offered. Just ask the attendant and he/she should be able to direct you. I was luck the last time I went and one of the shuttles was just pulling out and I asked for directions to the convention center not knowing about this service. They will give you a card with a phone number to call when you are leaving the show to take you back to your car.