You can also try running a spoon across it on a flat surface. Insert one end of the quill under the bottom thread, and pull the stitch snug. Flip the quill up and take a stitch over it as you did below, making sure the needle comes out on the side away from where the quillwork will be. Now bend the quill back down over the stitch and sew it down again at the bottom. Make sure that your stitches stay on your drawn lines.
Straight lines are essential here.
Continue on in this manner until you come to the end of your quill at the bottom line. This is where you splice in another quill. Sew down the quill, pull the stitch snug and make a fold in the quill as if you were to continue on. Pull on the quill slightly so that your last stitch loosens up a little. Flatten another quill and insert it under the first one.