Once you have cut the pattern pieces out you stitch together the shoulder seams of both the main fabric and lining fabric. Then pin the main fabric and lining fabric together with right sides together. Stitch around the armholes, neckline and bottom of the back piece leave your side seams open. Once you have sewn around the armholes and neckline, and back, clip your curves and turn through to the right side.
Now, pin the sides seams of your main fabric, right sides together, and sew. Do this on the other side. Then close the gap in the lining at the side seams using a slip stitch.
The full instructional video is on their YouTube Channel and the project probably only takes an hour or so.
A patchwork version of this would be lovely and a great way of using your offcuts!