A conclusion is simply a way of wrapping up your essay into one neat little package for your reader.  What is the main idea in your essay, your thesis?  You want to remind your reader what that is.  And you also want to review for your reader the points you made in the body of the essay, the points that support your main idea.  A conclusion is not meant to present any new ideas for your reader.

Let me give you an example.  If I were writing a paper on why we need amnesty for immigrants, I might have a conclusion like this:

Amnesty for unlawful immigrants is a necessity in the United States today.  We need new and different ideas from other cultures.  We need the productivity that immigrants provide.  We need to stop wasting our resources on tracking and deportation, money best spent on more serious and dangerous problems.  Our economy would benefit from the taxes paid by legal immigrants.  And our entire country is founded on the ideas and energy of immigration. So, amnesty should be provided as well as a path to citizenship.

This conclusion wraps up a paper on this topic, telling the reader my main idea, amnesty for immigrants, as well as the points I have made to support that idea.  This is what you need to do, wrap up the entire essay in that one small package of a conclusion.