Step 1: Unscrew the seats to remove them.
Step 3: If your cushion is as nasty as this, chip away at it so you can replace it with a new one.
Step 4: Cut out new foam for the seats.
Step 5: Anchor cushion to the seat board with spray glue.
Step 6: Cut out fabric to fit the seats.
Step 7: Wear safety glasses while using the staple gun!
Step 8: Staple fabric to the seats. Use common sense on how to fold around corners and such.
Step 9: Screw the seats back on.
Step 10: Admire your beautiful new chairs!