Hi Emily and welcome to SF
The only thing that I can think of is that because you just joined and only have a few posts, you aren't considered to be a "member" yet so certain restrictions apply. That could "possibly" be why you don't have access to post in that sub forum.
Anyway, I've made you a "member" now so hopefully that's fixed the issue. Can you please clear your cache and cookies and try again and please update us here as to whether that has fixed that issue or not.
Thanks for bringing it to our attention and I hope that you find what you're looking for here!