Please look around to see if your question has already been asked (and maybe even answered!) before you ask. It’s also perfectly fine to ask and answer your own question, as long as you pretend you’re on Jeopardy: phrase it in the form of a question.
It's not exactly clear to me what the last sentence means. From how I understand it, users should never report the answer of their own question, if not in the form of a question; in most of the cases, I think that if the user who asked the question would add an answer that sounds like another question, the answer would be probably merged with the original question.
Supposing that a user find the answer to the question s/he posted after week of searching, and before anybody else answered or gave the correct answer, can the OP write an answer reporting what s/he found to be the solution?