Exams below dan rank?

The page says "Passing an exam below your Dan rank awards 50% EXP of an equal-ranked exam. (only applies if your skill rank is Dan 1 or higher) "

How do you go about entering a dan test below your level? (I can't find anyone else with a dan rank equal to mine)

If there are others registered for the same skill but higher rank, and there aren't enough people, the server will try to get people from lower divisions to join automatically. You will be prompted if you wish to join.

any time there aren't enough people at your rank when tests are about to start, and there's a lower test available, you get a yes/no prompt offering you a spot in that test. If you want to do it, you need to click yes before the test actually starts , IIRC you have 10 seconds.