Questionnaires and showcards consititute a second form of documentation, available online at http://www.iser.essex.ac.uk/ulsc/bhps/doc/
Click on the ``Volumes, Questionnaires and Showcards'' link on this page: this gives access to codebooks, questionnaires and showcards for all nine waves, in Adobe Acrobat PDF format (read onscreen, print or download to disc).
Continue to explore the documentation and the questionnaires until you are familiar with the structure of the information they provide.