I agree with Mark's answer except I would add that the first step is to click look at your question then click on the Post an Answer button.
Try it. Say thanks to Mark.
I am a very literal person - when I first got help with a clue, I hesitated over the 'post an answer' box, because to my mind I wasn't posting an answer. I was looking for a reply/respond/comment box, till I realised this wasn't an option.