First, create pins for the part. Position the mouse pointer where you want the connection point of a pin. Then, use the keyboard command ap to start drawing a pin. Extend the pin as far as you want, then click the mouse again. This creates a single pin.
You can draw another pin immediately. gschem stays in the “add pin” mode until you change the mode to something else. When you are done adding pins, type s to enter the “selection” mode.