How do a start a discussion in a sub-forum?

[Phuong Tran]

I am still in my early days of navigating the site. I came across the Grand Rapids member sub forum in MI, but can't figure out how to start a discussion in that forum specifically. when I hit the blue Start a Discussion button, it's for the overall site.( I found the site tutorial at one point, and now can't find it again.) Can someone help orient me? Thank you from a newbie.