Use course tools>>Discussion Board>>Use archives
You can archive the messages in a Discussion Board forum for future reference. To do so:
Enter the Discussion Board forum you want to archive.
Click [Click Here for Archives].
Click Add Archive .
Enter a title and description for the archive.
Click one of the options for displaying the text:
Smart Text displays the text as it is entered but converts URLs and email addresses into links.
Plain Text displays the text exactly as it is entered, with no links.
HTML codes the text you enter with HTML tags.
Note: You can also format text directly using HTML tags.
Indicate whether you want to make the archive available to students.
Click Submit to add the archive.
Note: Click Cancel to return to the Discussion Board without adding the archive.