Brother HL-4200CN - Manual (Page 57)

LOADING PAPER AND USABLE PAPER TYPES 3 - 9
7
Hold the paper tray with both hands as you align it
with the opening in the printer and gently place it in
the printer.
8
Push the paper tray completely back into the printer.
Do not use excessive force on the paper tray. Doing
so could damage the paper tray or the inside of the
printer.
There is an indicator next to the paper tray that tells
you how much paper remains in the tray. Use this
meter as a guide for refilling the paper tray.
9
When printing A4 or Letter size paper, lift the
stopper on the top cover.