With a 45 (or half the length of theinch string, put one end of the string at the center of the wrong side of the fabric and swing your string around in a circle marking your fabric with a chalk.

Cut fabric at the chalk line and now you have a 90 inch circle
Sew a half inch hem all the way around
To add trim such as fringe or a large welt you need 8.50 yards.
You can buy ready made 2" welt's in solid fabrics. Just stitch it on per instructions
For a 3" or 4" fringe, lay it on the edge with the bottom of the fringe hanging at the edge of the skirt and top stitch it on.