Hi Bev,
First of all, I want to tell you that having a forum for jeans is an excellent idea from a marketer's perspective.
I just visited your forum and saw at least three different themes integrated, jeans to duct tape. I strongly recommend you to separate them. I would focus on few thing first and work on the others when you have steady growth.
For jeans, customize your forum little bit more like a jean forum and make some interesting threads. Such as jean reviews and price discussions...etc. and keep working on it.
Few more ideas..
Best places to buy jeans
Quality tests
Brands - cons and pros
Trends
Price watch - make people post how much they spent for a jean..etc
How to wash or care your jean
..
and do the samething for different topics...duct tape idea was very nice and interesting
Good luck!