1. First, take out the bedside armrest from the carton, and unfold the bedside handrail 90 degrees to make it vertical.
2. Next, flip the bedside armrest upward 90 degrees until you see that the positioning pin holes on the connecting tubes on both sides of the base are aligned. Insert the C-shaped latch into the hole to fix the armrest vertically.
3. Then tighten the handle screws on both sides of the bedside armrest. After tightening the screws, if the handle of the screw rod is not aligned horizontally with the base, you can pull the handle outward and rotate it to align with the base.
4. Finally, lift the mattress, place the base of the bedside armrest steadily on the bed board, leave a gap with the bedside fence, and put down the mattress.