How to write a summary:

A summary is a compressed version of a text. 

It informs the reader about the text's content.

It does not contain details.

It's language is formal and it its written in the present tense.

To write a summary of a text you have to structure the text first of all.

--> Divide your text ot the The Massacre at Wounded Knee in paragrahs

A story arc can help you do it