write a letter to your friend expressing your views on peace and harmony.
Since this is creativity based question that can improve your writing skills, so we advise you to attempt it of your own. However, following links, one one informal letter format and other on Peace and Harmony might give you ideas of framing the answer after elaborating the same.
https://www.meritnation.com/ask-answer/question/state-2-ways-through-which-we-can-bring-about-peace-and-harm/social-science/8805135
https://www.meritnation.com/ask-answer/question/is-it-necessary-to-write-the-name-of-sender-at-the-top-of-le/english/3919610
Hope these help you!