Megan, I think I've sussed your problem. Try clicking on the POST REPLY button at the bottom left of the screen under the most recent post. Then type in the blank box on the right of the little smilies.
Quick tip: use the "Quote" button when you want to give a detailed reply to a comment or where there have been other people posting in between. For example, say Excalibur has posted something you want to reply to but I and Rosemary have already posted other stuff. Click on the "Quote" button for Excalibur's post and then type your response below that text.