All you need is knit fabric and regular sewing supplies. I actually used an old knit sheet, so I'm not sure how much yardage you'll need. It was a twin size if that helps.
First, cut out the circle skirt. Instead of drafting a pattern, I just measured on the actual fabric and pinned where I needed to cut the circle. If you need help with a circle skirt, go here.
I made mine a little longer in length and cut the top opening a bit narrower since I wanted it to sit higher on my waist.
Now cut out your top. I used a shirt as a template. Notice it's folded at the bottom. I wanted the top of the dress shorter than a regular shirt because I wanted the waist line to be higher. Also cut out your sleeves {not shown}.
Cut out two long strips of fabric of different widths for the ruffles around the neck.
Sew the top front and back pieces with right sides together at the shoulder and side seams.
I cut my sleeves wider so that I could gather the bottom. This is optional.
If you do gather the bottom, cut out two strips of fabric to use as binding on the bottoms of the sleeves.
Stitch the binding to the sleeve right sides together, close to the bottom edge.
Turn it under and topstitch along the binding. Do the same for the other sleeve.
Sew the sleeves along the underarm seam.
Turn the sleeve right side out {the top should still be inside out}. Insert the sleeve into the top and stitch in place.
Lay the smaller ruffle piece on top of the wider one with right sides facing up. Run a gathering stitch along the edge of the ruffle pieces so that they are together.
Lay the ruffles along the neckline and adjust them to fit. Sew the ruffle together in the back, so that it is a complete circle.
Pin the ruffle along the neckline. I didn't want to finish the edges, so I pinned the ruffle a little above the edge of the neckline to make sure the neckline wouldn't show. Stitch the ruffle to the collar. You could finish the neckline with binding, similar to the sleeve, if you like a neater look.
Then turn the top inside out and insert the skirt into the top so that right sides are together. Stitch the top to the skirt and you're done!
This is a completely adaptable dress. You really could make any top and add it to a circle skirt using the same method.