The first thing you might want to cover in your talk is the historical background of the book. You should discuss the rise of Hitler and the role of the Hitler youth. As many people look back and wonder how anyone could have supported Hitler, you should emphasize in your presentation of the first part of the book the reasons why Hitler was so popular in light of the aftermath of World War I and the collapse of the German economy. Here, you might give some background about Susan Campbell Bartoletti's Hitler Youth: Growing Up in Hitler's Shadow, a nonfiction book she wrote just before The Boy Who Dared, and which provides much of the context for it.
If your teacher allows an interactive activity, you might stage a debate among your fellow students, with half assigned to advocate joining Hitler Youth and half against it.
Next, you should present a biography of Hübener, detailing the main episodes which inform his gradual transformation from support of Hitler to resistance against him, in particular the episodes in which he sees mistreatment of Jews.
The final issue you might discuss is the role of the BBC (British Broadcasting Corporation) in countering Nazi propaganda. Another possible activity here would be making parallels to our own lives now. What impels Hübener's resistance to the Nazis, and becomes his own force of resistance, is in part, his access to and respect for objectivity in media, and looking beyond Nazi propaganda to other sources. How many of your fellow students really keep up with the news? Do they seek multiple viewpoints, or only access one side of the story (such as Fox News)? Would this make your classmates vulnerable to the demagoguery of a contemporary Hitler? Ending on this note would not spoil the ending of the book, but would leave your classmates with a serious and important issue to consider.