The Silmarillion is the story behind the Silmarils and the desire to have them. In The Silmarillion there are wars, The Years of The Trees, The First Age, and Many other stories, Such as "Beren and Luthien". If your version has "Alkallabeth" and "Of the Rings of Power and the Third Age", you will have read about The Fall of Numenor and about the Rings of Power and the Third Age before the events of "The Hobbit" and "The Lord of the Rings". It is a great book to start reading and finish reading. Well, I hope this helps.