The BlackBerry Storm did not come with a lock/unlock option. Here are some directions on how to download an application to make it possible.
On your BlackBerry Storm go to the download icon. Once you have it open select App World. Search for the BlackBerry Slider application using the search option. Download the BlackBerry Slider application. Once down loaded you can slide the bar over to unlock your phone. You can also set the application to your convenience keys to lock your phone from there.