If you post a question and someone replies with information that you can use, it's a good idea to mark their reply as either helpful or correct. That way, others who have the same question can quickly see which replies might be most useful for them. A helpful reply is on the right track, while a correct reply answered your question. Keep in mind that you and others get more status points for posting replies that are marked as helpful or correct! When you feel that your question has been answered, you should mark the original question as answered. That way, people will know whether or not to keep trying to answer your question.
To mark a response to your question, go to the question in the community, look for responses, and click Helpful Answer or Correct Answer on each response that fits.