Or you want to cancel the photos, click the "x" button to cancel the photo you chose. Or you want to change/add more photos, click the button of "insert an attachment" to select photos and insert them. At last, click the "submit" button to be done.
You can write the reply/comment at the end of the page and click the "submit" button. Or you can click the "reply" button in the left lower corner of each topic/comment.