Gather upholstery tools and materials. Take fabric off chair by pulling out staples with a staple puller (upholsterer's staple remover -- Image 1). Be sure to remove all staples and tacks. Never place new fabric over the old material. If you do, when you go to clean the new fabric, the stains from the old cover could come through. Take old webbing (Image 2) and padding off the chair.
Put on new polypropylene webbing in a basket-weave pattern by doing the following: Start in the middle, fold over the end and staple in place (Image 1). Use a bar clamp to hold the webbing down. Gently rock the webbing stretcher (Image 2) until the webbing is tight. Staple the end into place. Cut the webbing, leaving an extra inch to fold over and staple down. Repeat the process for the other strips from front to back. To add horizontal webbing, repeat above steps and weave the strapping under and over, alternate weave (Image 3) in remaining strips.
Lay pad onto oversized 1" high foam (available at most fabric stores). Trace outline of pad on foam and leave 1/4" all way around. Put foam on top of webbing with spray adhesive. Lay 1/2" thick bonded dacron on top of foam. Trim dacron 1/4" bigger than pad. The dacron will give the seat a nice crown effect.
For four chairs, it will take approximately one yard of fabric and 1-1/2 yards of fabric for six chairs. Be sure to leave at least an excess of three inches of fabric all the way around the chair seat.
To attach fabric, first find the center front width of the pad and back, and mark. Do the same on the back and make a center mark. Find the center of the fabric. Fold fabric along center line and cut small notch (Image 1) for both front and back. Starting from the back, fold the fabric over and line up the notch with the center mark. When fabric is straight, start attaching staples, leaving the corners alone. Repeat above step to attach the front and then the sides. Use your spare non-stapling hand to smooth and straighten the fabric as you're stapling. Don't stretch the fabric so tight that the lines (if you're using striped fabric) are distorted. Trim extra fabric away.
At the corners, fold fabric over and pull down and away and staple in place (Image 2). Rotate the seat pad and repeat the process for each corner. Staple on dust cover material to hide staples and ends of fabric.