First make sure you are signed in.

The 2nd most common problem is that the post you are trying to comment under, currently has no replies. To be the 1st person one of the easiest steps is to click on the box that says "action" Change it until "quote/reply" comes up in the box, then click on the word 'Go" Next to the box. The window then should change with the message you are replying to listed in the box. You will then need to delete that message and type in your own in that spot. Hope this helps.