Two-person assembly: Lean headboard against the wall near desired placement. With one person holding the side rail up against the bracket, hand-start bolts (to avoid cross-threading) and tighten.
One-person assembly: Start with the headboard on its back and invert the rail to install. Ensure all bolts are tight before tipping down.
NOTE: If you experience difficulty aligning bolts with t-nuts, loosen up the headboard bolts.