John Lewis 800/65503 Instructions Manual page 3

Step by step assembly instructions
Step One
Fix the Siderails (3) to the Headboard (1) and Footboard (2) using Bolts (A) as shown in the diagram below.
Tighten using Allen Key (C).
Repeat for all 4 corners.
Step Two
Lower the Slats (4) onto the Siderails (3) and secure using Screw (B) as shown in the below diagram.