The Roundup Pump 'N Go sprayer is sold filled with a liquid product that you can use to eradicate and prevent unwanted weeds in your lawn. Once you use all of the supplied product packaged in the container by the manufacturer, you don't have to discard the container. Instead, you can refill the Pump 'N Go sprayer yourself -- no special tools required.
Push down on the pump handle and turn it counterclockwise until the handle locks into position. Perform the task outdoors in a well-ventilated area, and wear gloves and safety goggles for the task.
Keep turning the pump handle in a counterclockwise direction until the lid becomes completely unscrewed. Remove the pump from the bottle.
Refill the bottle with the herbicide product designated on the Pump 'N Go spray label. Replace the pump and screw it back into place by turning it in a clockwise direction until it becomes secure.