You have it right, for slow speeds for knurling, cutting threads, etc, first open the headstock cover and rotate the spindle to locate the bull gear pin. Once you find it, pull it out as far as you can, then engage the back gears by pulling out on the knob. The reason for pulling the bull pin first is because if you engage the back gears first, you will not be able to rotate the spindle to access the pin.
Going back to the higher speeds is just the opposite, disengage the back gears with the knob, then push the bull pin in while rotating the spindle pulley and holding the bull gear still. The pin will pop in once one of the two drive holes lines up with the bull pin.
ON EDIT: By the way, there is no such thing as a silly or stupid question, except for the ones that you don't ask!