Hi. Take a look at this
example. See anything you can use. It should be fairly easy to understand the code even if it's poorly commented. Don't ask me exactly how the javascript works. I just copied it off somewhere. It was pretty easy to adjust to my personal needs though.
There are sub-categories for
hardware / build. Just click and be amazed.
If you would rather have the menus at the top dropping down I think it's just ordinary positioning. Havent tried it...
About jserr.html: if I understand this correctly, a browser which is not js capable will receive some kind of return value from onClick="return toggle('menu1') and this will force it to follow the link instead. So it's a good idea to have a page for non-js browsers (jserr.html that is).
Otherwise, these are ordinary links. You can use them to load anything you want in the
bottom field, or did I get this one wrong?