Even if you don’t know the game which you want to play, just like in a brick and mortar casino, you can simply ask the dealer to explain it to you. However, that shouldn’t be a problem in most cases.
Note, that unlike most ordinary online casino games, Live Dealer games are only available for real money, so you won’t be able to try them out first. All you need to experience Live Dealer games is a decent PC or a MAC and a fast internet connection.