Step 4: Sew the top edges
HINT 2: At the beginning of each seam backstitch and then stitch over your start point to prevent unravelling, backstitch over your sewing line at the end of each seam too, this helps prevent your seams pulling apart.
On the wrong side of the main piece mark a line 3" (7.5cm) from each short side. Fold the fabric over to meet this line giving a 1 1/2" (3.75cm) hem and sew down with two rows of stitching 5mm or 1/4" apart. The large channel will form the casing for your cord. If you prefer to run your cord through eyelets, turn in a small hem on each short side and place an eyelet 2.5cm or 1" in from each edge and one centrally between these two.