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).  If there are two tanks for BK, as in the Epson Et-14000 model, fill both.

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 Black ink.   Also add Paper Saver Ink to the color tanks (C, M, Y) at least to the 2nd lowest fill line. 

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.