Locate the side rails for the bed. These will be long pieces (about 5 feet).
Locate headboard. The headboard and foot board of the bed will look similar, about 3.5 feet wide. These pieces go at the top (head) and bottom (foot) of the bed. They will be distinguishable in a sleigh bed because the ends of them curl under like the end of a toboggan.
Place a screw through one of the slats and into the screw holes on the headboard. Repeat with the other slat and the other side of the headboard.
Place a screw through one of the slats and into the foot board. Repeat with the other slat on the other side.
Locate support slats and place those about 1 foot from the top and bottom of the bed.
Place the support board on the frame.
Place the mattress on the support board.