AFAIK there's no way to hide the notification bar using stock settings and TouchWiz. You can, however, install a third party launcher that allows you to hide it, like Themer. I'm not sure if Nova, one of the most popular homescreen replacements, can do this as well, I had issues with battery drain in the past, so I stopped using it.
You can, of course, also root your device and apply a patch or install a ROM that allows the notification bar to auto-hide.