Using the lino cutter tool, start shaving or peeling away all the grey areas of the pumpkin. When starting, just peel off the skin. Once you have peeled the entire grey areas you can start going in and detailing your pumpkin.
If you can image the more you shave away the lighter it will become. Take your time and go slow with this step. Also you can use the detailed image of Karl to see where to place highlights and lowlights. From time to time stop and place the candle inside the pumpkin and turn off the lights to see how it is going and how much more you need to shave off. (DO NOT SHAVE OR CUT OUT ANYTHING THAT IS BLACK IN THE IMAGE)