If you want a really easy way to reformat dates(and time) I would get the free plugin by FLEXITONE called "PHP DateTime Formats". You should find it on the adobe DW site.
You use it by selecting the the date field, box etc etc then in the bindings tab on the right hand side when you click on the format section the plugin is listed, then select how you want it to be from the list. it throws the right php format code in and away you go. It is indispensable !