Convert simple data menu list to AJAX expandable

We have a blog page written in ASP that has a simple menu on the right column - <[login to view URL]> - that is fed from the database and has a top level and when that is clicked - opens to lower level items that are under that item. The problem is currently the page rebuilds so when we have a long menu - the newly displayed menu is below viewable range without scrolling. I would like to have a sample made that would give us the template to convert all these to AJAX style where when you click the top level item the lower items under that item display without rebuilding the page.