With RS together, (inside out) pin and stitch bottom hem of lining to bottom hem of dress, matching side seams. Press.
NB: Because this dress is fully lined, it's easier to shorten hem now rather than after it's finished, so try is on now. The pattern is about knee length on me because I'm not very tall - 160cm (5'3"). If you'd like a true mini dress, measure and cut off evenly from the bottom hem, remembering that it will be 1cm (3/8") shorter after hem is sewn.)