Replies to a question appear in order of rating (rather annoyingly IMO as it makes threads a little difficult to follow) so if you want to add a point to your question or clarify a point simply post a reply to your own question, give it three stars and it will appear at the top of the other replies where people can see it.
Personally, I've stopped rating answers to my questions, because I find them too vague. It's probably more useful to post your own response pointing out which answers have been (un)helpful and why. And (as boognish76 implies) ratings mess up any thread where the chronological order of answers is important.