As it faces you, the spring attached to the opposite side of the wood (where the vacuum is), with the upholstery material wrapping down the front, back and sides of the spring and wood, and being nailed to the wood with the spring sandwiched inside.
After that was done, a piece of cloth that has been painted (similar to the cloth I make to reproduce historical military equipment; i.e. oilcloth), was nailed over the raw, exposed edges of the upholstery for the entire length, and width of the wood EXCEPT in the the rear of the spring ( to your left), where a piece of upholstery material entirely of a different pattern was painted on one side and tacked over the raw edge of the seat upholstery in an arc.
It also appears that there was a thin sheet of material from front to back covering the hole to keep out dirt and critters. (it's a brownish tan color).



