Focus your discussion on the connection of your theme to the underlying meaning (content) of the artworks and the historical/cultural context in which it was created. A small amount of biographical information on the artist may be appropriate, but more emphasis should be placed on the artist's artistic style and its relation to art movements.
Consider investigating some of the following questions. You are not limited to these questions. They are intended to help you get started writing the essay/slide text.
Start exploring possible topics and learn more about the history of art from these book selections.