The following forum message was posted by brlcad at http://sourceforge.net/projects/brlcad/forums/forum/362511/topic/4075794:
You're probably not doing anything wrong other than just not knowing how to
use MGED. It's not a discoverable interface -- it requires training. There
are beginner tutorials on the website to get one started that take most people
about a day to get through. (Tools->GeometryBrowser might help too).
That said, the DLLs should certainly work with Visual Basic but I'm not aware
of anyone that has tried. The documentation "source" files are XML which are
then processed into HTML and PDF when a source release is produced. If you
don't have xslt/fop processing tools set up on your system (which you probably
don't if you had to ask), then you'll probably be best off downloading one of
the binary linux distributions and reading the html docs.