Ok. There are two "groups" of GPIO pins labeled GPIOA and GPIOB. But within those groups are pins from several ports. You just have to search through until you find the right one.
PTG3 (the one I'm using) is "Pin 19" of GPIOB. Note: "Pin 19" has nothing to do with the hardware pin on the microcontroller. It is merely the designation within the Init_GPIO component.