1 Macbeth went to see the witches
Macbeth wanted to understand what's going on. He went to see the witches to figure out what's happening to him.
2 Macbeth was told he can't be harmed
Macbeth was told that he can't be harmed by any man born from a woman. He was also told that he won't be defeated before the Birnam wood marches towards him. See Summary of act 4 - scene 1.
3 Macbeth was warned of Macduff
The witches warned Macbeth of Macduff. Macbeth decided to kill the later to feel safe. Macbeth knew that Macduff fled to England.
4 Macduff's family were killed
Macduff's family were killed by Macbeth men. His wife and son were killed. See Summary of act 4 - Scene 2.
5 Malcolm and Macduff decided to fight Macbeth
Both Malcolm and Macduff agreed that fighting Macbeth is the right thing to do.
6 Macduff knew about his family
Macduff knew that his family was killed by Macbeth. See Summary of act 4 - Scene 3.
7 Macduff wanted revenge
Macduff wanted to kill Macbeth to get revenge. Malcolm told him to put his grief into action and Macduff agreed.