Buy the ink including a needle and a bottle of ink.
With your computer on, select the printer properties option, select the Replace Potion option inside Advanced in Properties, and the printer's ink cartridge will move to the center and be manually removed. There is a pinhole under the label paper at the top of the cartridge, some brands of cartridges do not have pinholes, you have to drill an eye yourself.
Insert a needle into the ink bottle to suck up all the ink, insert the eye of the needle, add ink, and load it back into the printer. Click Replace on your computer to finish.
Remember to seal the eye of the needle with tape after filling the ink.