This is good question. An essay basically has three parts. First, it has a thesis, which is the most important part of your paper. In this section you are making a point, which you will defend for the rest of your paper. A thesis is debatable. So, you will need to defend it.
Second, the body of the essay is your proof. In other words, this is the section where you seek to defend your thesis and refute those that might disagree with you.
Finally, you have a conclusion. In this section, you are wrapping up your findings. You are letting the reader know that your supporting paragraphs are now finished and these supporting paragraphs have confirmed your thesis. It is a good place to summarize your findings. Do not add something new; it is time to go back to your thesis and show how the body of the paper has proved it.