We can't do any sort of full summary in this space -- that's just too long of a question. You should look at the study guides on here. They are quite good at giving you the basics of the various acts and scenes.
A brief summary of Act II would be that it revolves around the killing off Duncan. First, Macbeth is stressed out because he wants to kill Duncan but is afraid and feels it's wrong. That's why he sees the dagger in Scene 1 and it's why (after he kills Duncan) that he hears voices accusing him.
In the rest of the Act, we start to see the fallout from this murder. The king's sons flee for their lives. Then, in Scene 4, we start to see unnatural things happen as an indication that the natural order has been upset and bad things are in store.
The beautiful thing about eNotes is that you can almost always find exactly what you need or want, and that is especially true of such well known works as Macbeth. I'm including a great site for you here. From that page you can find whatever analysis and insights and summaries you need. As always, I encourage re-reading the work first, to glean all you can before relying on the insights of others, and re-reading after you have gotten some help so it becomes more clear to you.
This is a great time to use what enotes has to offer! I have found that reading a summary before reading the play is very helpful to make sure you follow everything and don't miss any nuances. You have the big picture before you wade in to the details. Enotes has fantastic summaries. So here is a link to the summaries:
There is also a summary and analysis for each act.