Dell 1250c Color Laser Printer - Manual (Page 39)

Loading Paper 37
7 Before loading the print media, flex the sheets back and forth, and then
fan them. Straighten the edges of the stack on a level surface.
8 Load print media on the MPF with the top edge first and with the
recommended print side facing up.
9 Adjust the width guides until they rest lightly against the edges of the
stack of print media.