Hi, this video will show you how - https://www.youtube.com/watch?v=aGtfZgNNSOI
Here you go! Hope that this helps you with the instructions and ideas.
Try this: https://www.hometalk.com/1709421/upholstering-settee-and-sewing-chair-cushion
Do you want to re-cover the setee, or re-upholster it?
The terms do not refer to the same procedure.
Re-upholstery means replacing the inside stuffing with new, and then sewing a new fabric covering for the outside.
Re-covering furniture means either taking off the old covers and sewing new, or covering over the old fabric with new: either way without touching the inside forms or foam stuffing,