The next step can be a bit tricky, but just take your time – you can do it!!
Use your Stitch in the Ditch Foot or all Purpose Foot and stitch either side of the zip – you will start to sew on the inside of the cylinder, re-positioning as you go.
You will now have this:
OPEN THE ZIP NOW! Now pin the right sides of the outer together and on the other side of the zip, the right sides of the lining together. The zip teeth will face towards the lining (I tried to get a photo with the yellow pin)