I would recommend adding content before you waste any money on traffic. You will get no sign ups with buying traffic if there is no content.
Its empty. Why should someone come and stay? Try to copy ideas for content from other forums! AND LEAVE YOUR SIGNATURE EVERYWHERE YOU CAN
Maybe you should get somebody to make some post in it first..no content, no visitors..Before thinking of getting visitors, isn't that you should think of getting more content? Good luck with your forum
first put some nice content and then submit your blog in blogs directories. Try Dmoz, yahoo and google!