What we're calling forums are actually tags. About the best you can do is go to the home page and pick the most likely. Best for the future is to start tagging the posts you might want to refer to. You will eventually have have a useful base of tags, but it will take awhile. I do know what you are talking about, and it doesn't happen here.
No instant email, so you should use the PM system. Go to the profile of whomever and click the PM button. Sometimes they are notified by email, and sometimes they won't know they have a PM till they log in to a2k.
Sorry not to have better information.