Fold your fabric so it's right side out again. It
should be facing right side up, with the zipper pull facing out. Fold
the fabric edge over again, so the fold just butts up against the zipper
teeth. Pin in place, and now sew a second seam as close to the zipper as
possible. If you don't have a zipper foot, don't fret, I didn't either.
The only tricky part is sewing past the zipper pull itself, and you
should be able to sew down to it, stop the machine, lift up the foot,
zip it past, and then resume sewing. Don't try and sew right past it.
You WILL get a wonky seam line.