You are correct, moderators can create announcements. You need to go to the control panel for the board you're a moderator at (cp.html). If you don't know the URL to the control panel, just ask the board administrator.
In the control panel is a menu item called Announcements, click it and complete the necessary fields and then submit the Announcement. Make sure and select a forum(s) for the Announcement to go to. Many people forget to select a forum and then wonder why the Announcement doesn't show up <img src="https://www.ubbcentral.com/boards/images/graemlins/smile.gif" alt="" />
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Doug
darksaber.hispeed.comI am altering the deal. Pray I don't alter it any further.
--Darth Vader, The Empire Strikes Back