Turn the printer on. Open the access door on the front. After the carriage has moved to the right and stopped remove the old ones from the slots and insert the new ones. If you have never done this, press slightly down on the old ones and pull out. To insert, slide the new ones in. They may go at a slight angle and then you have to ‘snap’ them up. When done, re-close the access door and then there should be instructions onscreen to align the cartridges.