Flemish Community (NARIC-Vlaanderen): download the form on http://www.ond.vlaanderen.be/naric/en/consulting-application-forms/.
French Community (primary and secondary education): download the form on http://www.equivalences.cfwb.be/index.php?id=1526.
French Community (higher education): contact the diploma recognition service. You can find their contact details on http://www.equivalences.cfwb.be/index.php?id=506.
French-speaking universities and university colleges: contact the Admissions Office. Check the Useful links section for their websites.