As said, there's no longer marketing "of the forum" (with some small differences that don't matter to you).
If you want to advertise a project, the route should be to find a campaign manager (and maybe an escrow too for the funds for the first few weeks, but the campaign manager can do that too) that will "hire" a number of users to advertise what you need in their signature space and/or avatar. Campaign managers: you can discuss with icopress or find lists like this one and see which one of them can help you. And you will need a designer for the signatures and/or avatars, but the campaign manager will advise you in that if needed.