its ' how do i market a forum ' and you can start by putting links to your forum in other forum signatures.
First, post yourself some good threads with different names in your forum...and submit a sitemap to google. Then,you will get a decent amount of traffic from google... start from there.
Write articles on sites and backlink to your own site. Try to get 10 other dedicated friends to post a lot in your forum. The more content, the moure that is searchable by google, and the more hits you will get.
what is so funny on what he said? You should focus on getting some new members to your forum. As you are doing this try to participate in your forum more. Don't expect others to do it for you.
Where does your traffic come from? Do you live on search engines alone? What have you done lately that is new for your surfers? Do you have a traffic buying strategy? If so is it profitable?
You could by some cheap guaranteed signups and see if they become active. Article marketing, yahoo answers and video marketing could work well if you have a targeted niche.