Starting at one corner, sew along the entire length of the curved edge.

I recommend using a stitch length of around 2 mm for this step, and on all future sewing steps.

At the beginning and end of your stitching, make sure to go forward and backward about 3-4 stitches to prevent the thread from unravelling.

Don't forget to repeat these beginning and ending overlapping stitches on all future sewing steps.

Your stitching line should be about 1/4" (6 mm) away from the edge of the material.

On many sewing machines, you can simply line up the edge of the material with the edge of the presser foot to achieve this spacing.

If any pins are in your way, you can simply remove them as you sew. When you're done sewing, remove any remaining pins.

After you finish (and after all future sewing steps) trim away all excess threads with your scissors.