There is no sign up, you just go. It is part of the Art of Entertainment series. There will be 3 classses...appetizers, entre, and dessert. Usually, there is a guest chef from one of the WDW restaurants. He will demonstrate the dish and everyone will get a small serving to taste. Then there will be a wine discussion by one of the wine stewards from the ship, again with a tasting.
There is no charge. They are held in Studio Sea, about 10 am on sea days. Check your Navigator. They hand out a copy of the recipes...sometimes each day, sometimes all are handed out on the last day.