what you'll need:
1. bed head frame (mine was a metal frame) - i.e. this won't work for an ensemble
2. staple gun & staples
3. a piece of thin MDF (as wide and high as the existing frame - your local hardware store should cut to size if you ask)
4. foam, approx. 5-10mm thick, enough to cover 3 sides of the MDF (i bought mine in a pack from spotlight)
5. fabric (enough to cover the MDF)
6. sewing pins
1. staple the foam, piece-by-piece, around 3 edges (or just the top edge and approx. 30cm on each side as i did - see below) of the MDF
2. place MDF board between mattress and bed head
3. wrap your fabric around the MDF & bed posts of existing frame, folding corners neatly and pinning so you have one side of the MDF presenting with a flat neat finish and all pins & folds on the reverse side - voila!
here's some step-by-step pics...