Step 1: For this zipper, it may be easiest to give yourself a 1" seam allowance, as it makes it gives you a little more room to sew a nice, clean zipper. To do this, cut this seam 3/8" wider than your normal 5/8" seam allowance.
Next, place your zipper in position on your fabric, marking the fabric where the zipper ends at the metal tab. Sew your seam up until the start of the zipper with a 1" seam allowance (or 5/8" if you didn't cut your fabric wider).
Step 2: Press the seam allowances open along the stitching. Continue pressing seam open past the stitching on the left-hand side of the zipper opening only. The left-hand side of the zipper opening should now be pressed open the full 1" (or 5/8") of the seam allowance.
Step 3: Turn the fabric over so that the right side is up. Press the other side of the seam allowance (now on the left-hand side) open 7/8" (of 1/2" if you used a 5/8" seam allowance).
Step 4: Pin or baste the zipper to the right-hand side of the zipper opening, with the zipper teeth as close to the folded edge as possible without covering the teeth (if the zipper is placed too close, the fabric will catch in the zipper when it is being zipped).
Step 5: Sew along the basted side using a zipper foot, with seams as close to the fabric fold as is reasonable. I like to start at the bottom of the zipper and sew up to the top so that everything stays nice and lined up. To do this, make sure you start sewing with the zipper all the way zipped up, unzipping only at the top to finish the seam.
Step 6: Now pin the left-hand side of the zipper opening over the right had side, overlapping by 1/8". Pin or baste, making sure to catch the zipper underneath.
Step 7: Starting at the bottom of the zipper, sew across the bottom of the zipper from left to right, turn 90 degrees, and sew up the left-hand side of the zipper, 1/2" from the folded edge. This creates the flap that covers your zipper. Use the zipper foot to help guide you along the zipper underneath.
Step 8: Inspect your marvelous work! Make sure stitching lines are straight and that the zipper does not catch any of the fabric as it zips.