To post a new topic in a forum, click the NEWTOPIC* button on either the forum or topic screens. To reply to an existing post, use the POSTREPLY* button.
If the button reads "LOCKED," the topic may be read, but is no longer available for comment. You will need to be a registered, approved user before you can post a message, regardless of the Topic's status.
A list of your permissions in each forum is available at the bottom of the forum and topic screens. (Example: You can post new topics, You can vote in polls, etc.)