It is simply a matter of replacing the cable.
If you are asking about how to open it -- it's actually much easier than you'd think. For a first timer (not an old pro who can do it without getting under the car

), lay directly under the nose of the car. If you look up at the bottom of the latch you will either see the metal tab where the cable goes in or just the metal tab with a hole in it. Simply pull the tab towards the driver's side of the car and it will pop.
