I use this as a headboard for a day bed.  I got a twin sized 10" memory foam mattress and a twin sized platform bed, and placed them lengthwise along the wall in a guest bedroom.  The headboard rests against the wall behind the bed.  No, it's not attached to the bed, but it doesn't need to be.  It stays in place with the bed pushed against it.  (It could be attached to the wall with L-brackets, I suppose.)   I used twin sized linens and pillows to dress the bed.  (All of this came from Wayfair.)   It makes a great addition to the guest room; a child can use it while their parents sleep in the larger bed.