In ACP > Manage > Privileges, select the category you want to allow guests to post in, and give guests the "Create Topics" and "Reply to Topics" privileges.
I'm trying to implement the adsense plugin:
It asks for an "Ad Slot Unit" number for different places to post the ads but I can't find the "Ad Slot Unit" in Adsense. It looks like it has been discontinued. Adsense instead provides HTML code.
All the Best,