Which version of JB do you have, 4.1 or 4.2? If you have 4.2, then you should have lock screen widgets. To add a lock screen widget in 4.2, swipe the lock screen from left to right to get an empty widget screen, then tap the screen. You may need to expand the current lock screen widget (e.g., the digital clock) before you can swipe left/right -- swipe down from the current widget to expand it.
You can drag existing widgets to re-order or delete (drag to trash).