1) Pause the software by hitting the Home button. 2) Click on the Miiverse icon. 3) There, you should go to Post. 4) While making a post, click the top right corner where the photo box is. 5) Add whichever screen you want the photo of, finish the post, and then hit the Post button. It'll be uploaded just like that! Not all games let you take photos, but Majora's Mask does!