Paper Saver ink goes in the tank marked “BK”, the tank for black ink.  (If that tank had regular black ink in it before, you’ll want a new compatible printer).

Wear disposable gloves and wipe up any spills with a damp towel.  Generally follow the instructions that came with your printer or instructions you find online but use the Paper Saver ink instead of the regular ink. 

Paper Saver ink goes in the tank marked “BK”, the tank for black ink. If there are two BK tanks add ink to both. Also add Paper Saver Ink to the color tanks (C, M, Y) to at least the 2nd lowest fill line
so the printer can perform its priming and cleaning functions properly
without contaminating the Paper Saver ink with regular ink. Each bottle contains 70 ml of ink. We recommend at
least 140 ml of ink for filling the tanks in a new printer for the
first time.

Specifically for the Paper Saver Ink:

1. Unscrew the large cap from the bottle, remove the seal, and screw the cap back on the bottle firmly.
2. Remove the small top cap and fill the printer BK (black) tank  with Paper Saver ink.
3. After filling, place the cap back on the bottle.  If the bottle is empty, remove and discard the label, and recycle the bottle.