You buy an ink refill kit, I-Print or Universal brands or similar. The instructions are in the kit. But basicly you peel back the label on the top of the ink cart and slowly inject up to 20 ml of black ink with a furnished hypodermic needle. It can be very messy if not extremely careful. With the color cart you must inject up to 6 ml of each color into the proper color hole. You can test color holes with a tooth pick. I have refilled over 50 times with no trouble ever at a cost of $2.50 per cart. Others have stated they almost always had problems.

The ink level meter will always read empty and can only be reset with a new ink cart from Dell.

Whichever one that you can feel the spongy material in. In most ink carts either one will work. Don't put in more than 20ml. of black. In the color, no more than 7ml. of each color.