That is a great chair, Lynn! Perfect for planting. I love it!
You can use window screen material or chicken wire stapled to the underside of the seat area and shaped to the depth you desire. Line with sheet moss or other green moss, add a light succulent soil mix, then plant. Don't stretch the wire tightly if you want to add the plants out the front or sides like in the picture because you will need to shape the "depth" of the planting area a bit deeper to accommodate the plants. The chicken wire has larger holes to poke plants through from the outside but the screening is less stiff and fairly easy to cut slits in if you are careful. After planting, add more moss around the plants. If you use chicken wire you can pull bits of the moss through the holes to cover the wire. If you use screening or some other material like heavy burlap or such, you will need to glue the moss on the bottom to cover the material. Does that make sense?
I can't wait to see yours!!