In order to create a rubric for a discussion board, follow the below steps:
1. Browse to the discussion forum that you wish to attach the Rubric to.
2. In the Forum Settings (see How do I create a discussion board? for more on accessing the settings) select Grade Discussion Forum
3. This will generate new rows called Due Date and Associated Rubrics. Click Add Rubric.
4. Next choose Create New Rubric.
5. All fields in the Rubric are editable and rows and columns may be added or removed:
6. Click Submit once you are have filled in all the information.
8. Later when you grading the discussion the rubric will appear when you are in the grading screen. (For more on grading discussions see the FAQ: How can I grade a discussion online?)