Peel off the wrapper. It isn't glued on, so this should take about 2 seconds.
Line your phone up on the back, and lightly mark where the top sits with pencil.
Measure about 2.5 inches above that and mark again. This should be close to the very top. Using this mark as a guide, draw the shape you want it to be. I chose to add a slight dip to the front to make it easier to take my phone in and out. On the back be sure to add enough space for the charger to get through to the outlet.
Use a sharp blade of your choice to carefully pierce the thick plastic. Grab your sharpest scissors and carefully cut along the lines. Repeat to make the outlet hole. This is the hardest part!
Viola! You're all done. Leave as is, paint it, add stickers, do whatever you want!