Discuss how to grow up a forum...

if you have an original niche, let say gaming the goal is to get

gaming fan-art
gaming cheat
gaming tutorial guide
gaming marketplace

The things are you need to contribute those and people will come, also other people might contribute those themselves once the forums reached some what a popularity
Also the design outlook is pretty important too. your forums look blank and ghost.

after all that you can move to SEO just google it do it yourself or pay someone to do it.