1. On the toolbar of the Open or Save dialog, click the arrow beside the
Views button and change the view to Details. (Or right-click in an empty
area of the window and choose View | Details.)
2. Click on the appropriate column heading to sort ascending. Click again to
sort descending.
3. Change the view back to your preferred view using either of the methods
in (1).
Alternatively, right-click in an empty area of the window, right-click, and
choose Arrange Icons | By <whatever you want to sort by>. This will only
sort ascending, however, even if you select it more than once.