North Americans do not need a visa for any country in Europe. If you are participating and you are not sure if you need a visa, you can check with the local Czech consulate in your country. They can advise you if a visa is necessary, how long it will take to process and how much it will cost. You should also check to see if you require a visa for the excursions destinations (Austria) and any other countries you wish to visit in Europe on your own.
Do I need a visa for the Czech Republic?