Use course tools>>Discussion Board>>Participate in a forum
To respond to a message in a Discussion Board forum:
If necessary, click the title of a thread in the forum to see a list of all the messages associated with the thread.
Click the title of the message to which you want to respond.
Click Reply.
Type your response in the Message box.
Click one of the options for displaying the text:
Smart Text displays the text as you enter it but converts URLs and email addresses into links.
Plain Text displays the text exactly as you enter it, with no links.
HTML codes the text you enter with HTML tags.
Note: You can also format text directly using HTML tags.
If you want to hide your identity and the option appears, click the box next to Post message as Anonymous.
(Optional) Attach a file.
Click Preview to see how your message will look in the forum before you add it.
Click Submit to add the reply to the forum.
Note: Click Cancel to return to the Discussion Board forum without adding the reply.