How do public car auctions work?

So I plan to go to a car public auction this week or next week. I will be going to the South Chicago Auto Auction of Harvey in Harvey,IL. This is my first time going there and to a car auction. Im interested in a 07 Chrysler 300 and other cadillac cars I saw on online. What can I expect and how do I deal? Is it good to buy cars from auctions?