OK so what happened is that Minato in a moment of paternal weakness agreed to let Madara have Kyuubi in exchange for Naruto's life. This led to Madara being able to attack the village.

Burdened by guilt, Minato decides emotionally to atone for leading to such loss of life in Konoha by both sacrificing himself and in doing so leaving Naruto with the power to exact true revenge upon Madara one day for he did. However, the rest of the village just see Naruto as being responsible for the deaths of so many in the village, as to save his one life so many had to die, so they hate him.

Madara's plan was to destroy the village with the Kyuubi, however his backup plan was in case of failure there would be at least a huge loss of life and the Uchiha would be blamed, as they would be suspected of controlling the Kyuubi. As a result the village would move against them, making things difficult and eventually leading the Uchiha to take drastic action, such as they coup they tried. The result of this would be that either the Uchiha would kill off the Senju or the Senju would kill of the Uchiha (which is what happened and he helped with).

Naruto now realises his true destiny and moves to face off with Madara and plans to expose this dastardly devil to Sasuke, thus hoping to bring Sasuke back from the dark side. Together the will then fight Madara and try to finish him once and for all, showing that together the Senju and Uchiha, as Konoha shinboi, are far more powerful than they are if they fight alone.