Write a summary of Act 1 Scene 1 of Romeo and Juliet.

To write a summary, read the scene and then tell the important events that occur and dialogue that is said.  Break the scene up into parts to make it easier. 

To start, for Act 1.1 of Romeo and Juliet, read the opening with the two men from the house of Capulet.  The summary would read something like this:

Alone on stage, Sampson and Gregory tease each other about which one is braver while they joke about and threaten the Montagues who, apparently, are a rival family.  Their dialogue reveals their hatred for the Montagues. 

You can add more details depending on how detailed your summary is supposed to be.

Next, two Mantagues enter the stage, and Sampson and Gregory try to provoke them.  It works, and they end up fighting.  One of the Montagues, though, Benvolio, doesn't want to fight and tries to keep the peace.  He fails.  Citizens, apparently fed up with this kind of feuding, attack the fighters, then the heads of both families arrive on the scene.

From that point on, just read the rest of the scene and write out the summary.  Summarizing is a valuable learning tool and will help you get a handle on what's happening in the scene.