I wanted moderators to post on my forum's announcements and rules and regulations. How can i make this? If I change the permissions of that forum to members, members can also post topics there. How can I make that the mods and admins can only post?

General>Categories and forums
Click on any forum name
Permissions tab
Create a sticky message
Create an announce

Check those two fields for moderators.

Hope thats what you wanted to do.

Thanks!