With the wrong side of the cushion material facing up, fold the fabric in half.
Take the foam pillow insert and place it on the fabric, making sure it is in the centre and you have enough fabric left on all four sides.
Using a sharp pair of scissors, cut around the foam pillow insert, ensuring at least one inch fabric is left over for ties.
Now you have two pieces of cut fabric, sew them together from three sides, leaving a space of almost one foot on one side of the cut fabric to allow the foam pillow slip into the cover. Also make sure that you baste about one inch from the edges of the fabric.
Once you are done basting all the three sides of the fabric, insert the pillow into the cover to check if it fits well. If the cover is too loose or too tight, adjust the stitching accordingly.
After adjusting the stitching, turn the fabric to the right side and slip the foam pillow insert into it.
Using your needle and thread, stitch the open side of the pillow cover, applying very small stitches.
Cut two strips (1x12 inches) of the same fabric you used for the cover.
Fold long edges of the strips in to the wrong side of the fabric and iron them to make the edges flat.
Fold each strip in half lengthwise, iron it and sew along it along its edges.
Hand sew each strip in place. These will later be used to fasten your cushion with the chair.