The fabric rows are laid on on my ironing board which I adapted with 3/4 inch thick plywood, 24X48 inches and just placed on top of my old ironing board base with thin strips of wood on the bottom to prevent the top from shifting. As others have described, I used batting and an old sheet to cover it and tacked that onto the underside with small tack nails. One could also use staples as well.
Here I used leftover scraps from the front for the back, as I was short of the red material. That is what comes from lack of planning in the beginning! I was very pleased how this turned out! One more Christmas gift was done!