Compose your message, click on 'go advanced' in the bottom right of your screen. Scroll down to 'manage attachments', then use the 'browse' just like before. Don't forget to click on 'upload' in the middle right after the picture is found. I have trouble remembering this part because it's on the right side when I'm looking at the left. After it's done, close the screen. If it doesn't look like the pictures loaded, don't panic until after you save the post.