A total of 6 DUNE books. A movie based on the first book, called DUNE, was released in 1984. I saw the movie after reading the book. First of all, DUNE makes a lot more sense if you had read the book. If you had not read the book, the movie is much more confusing and boring.
Spice is used to fold space- travel without moving.
Therefore Spice is valuable. Emperor Shaddam the IV is sending the Atreides to DUNE and is moving out the Harkonnens at the same time. The Atreides are supposed to go and live on DUNE for a short bit, while the Emperor gives the Harkonnens extra troops to destroy the Atreides so there is no more feuding and fighting between the two. I don't want to spoil any of the surprises, but other parts of the plot involve a traitor and the local people of Dune called the Fremen. The actors they picked for this movie are ho-hum.