The underskirt is composed of three large rectangles of fabric. I’m going to assume that you’re about 5’6” tall and planning to wear low heels - add or subtract a little as you wish for your own particular needs.
1. Cut three lengths of 110cm (44”) which are all the full width of the fabric (ie three almost-squares), and sew the three together along the selvedges [the edge of the fabric as it comes off the roll] to make a tube. Don’t forget to leave about 15cm (6”) open at one end of one of the seams so that you can get the skirt on when it’s finished! Press your seams open, and continue to press the edges aside along the opening, as if you had sewn all the way along to the end. Diagram
2. Now do the same with the lining, ensuring that it’s the same width and cutting a bit off if not.
3. Slip the skirt inside its lining with right sides together.
4. Sew the lining to the outer fabric around the hem (bottom) of the skirt. You may want to hold the skirt against you to check the length, but don’t forget to allow a little for the seam allowance at the waist and extra length for the possibility that you might wear heels with it! This is a very quick and dirty method of hemming a skirt, but since the underskirt will mostly be hidden, we don’t need perfection. Also, of course, you can always make adjustments later.
6. Once you’ve pressed all your stitching, turn out to the right side and press, then baste the top edges of the skirt and lining together. Sew the lining to the outer fabric neatly around the opening, along your fold.
7.At this point you have three options:
For a quick Hallowe’en costume result you can gather the waist, which isn’t period but may be “good enough” for you if you’re going for speed - again, this skirt will be hidden so this may be a shortcut you want to take. Hand or machine sew along the top with a big stitch and pull the thread so that the fabric bunches up to your waist measurement. Tie the threads and sew the gathers down.
At the other end of the spectrum, for period accuracy you may want to cartridge pleat the top. There are so many good online tutorials for this, such as this one, that I won’t repeat the method here.
However, on my pirate dresses I went for a good option in between the two: knife pleating. It’s easier than it’s sometimes made out to be and gives a pleasant effect. Click through to the next page for full instructions.