Ink jet printers will eventually run out of ink and will need to be changed. Be prepared for this by recording your printer model and buying the correct ink cartridges to fit in the printer. All printers do not use the same cartridges, so take care to get the proper ones. You will eventually need at least a black and a color cartridge but they may not run out at the same time.
Next, open the top of the printer so that you can see the inner workings of the printer. A small cart carrying two ink cartridges should swing to one side of the printer. Once it has come to rest, release the latch on the top of the ink cartridge and gently pull it out of the slot. Remove the plastic wrap from the new ink cartridge and then insert it into the printer in the same spot you took the old one from. Make sure it is securely fastened and then close the lid to the printer.
After the lid has been closed, it may take a couple minutes for the printer to recognize the cartridge and realign itself. It will then print a test page to ensure that everything will print correctly and make sure that there are no major problems on this page. Once that has been completed, it is safe to continue printing other jobs.
Changing a laser ink jet cartridge is similar except the cartridge is generally much larger and in the shape of a tube instead of a rectangle. You will need to find the ink cover and lift the hatch to gain access to the inner workings of the printer. From there you will be able to pull the old cartridge out of the printer and replace it with a new one. These tend to be more expensive than ink jet printer, but can last longer and look more professional.