HP Deskjet 6122 Color Inkjet Printer - Manual (Page 21)

1. align the arrows
For legal-sized paper, pull the length guide out beyond the edge of the
tray, load the paper, then slide the length guide against the edge of the
paper.
load paper in the tray
If you are using a paper size different than the paper size last used in the 250-Sheet
Plain Paper Tray, then you must set the paper size .
Follow these steps to load paper:
1. If necessary, remove the lower tray from the base.
4. Set the paper length guide by pulling it until the arrow lines up with the paper
size.