How do I create folders and add/update Javascript (use a jQuery framework for my site) on Google sites?
To make new folders, just add a new page (for example "foo"). Then when you add a second page (called "bar" for example) you can select that it go under "foo" (so the result is http://sites.google.com/site/yoursitename/foo/bar/
as for javascript, I think you have to build a "gadget" (see http://sites.google.com/site/gsunhelp/step-by-step-guides/buildinggadgetsforgooglesites)