A good question is: "Would you want to join your site?" If you stumbled across you site, would you join it? What would put you off joining? First impressions, for a new forum you have way to many sections. Condense them down for the time being to make the forum appear more active. This is the first thing I look at if im going to join a forum. If I see too many empty forums, or threads without replies, it makes me think "Will I be wasting my time posting?" All the best
Do you wanna spam.I can give you the method. Automatically sign up , no need to advertise any where and so more.
Try to make a quality forum like: -make a variety of essential category -control illegal topics and post by a good administrator. -provide popular add. -make attractive graphics and other service.
invite, invite, invite! that's how it is! or pay people (or give incentives) for people to join your forum.
Well, I think the best way if you have a good budget you can try to buy forum posts. This will cost you any thing between 2 to 5 cents per post so you will need a starting capital of $200 to $500 to have 10000 posts.