At this point you should have all your pieces if not see this post on cutting the dress completely out of old tee shirt.
Now a few quick notes on sewing knit fabric.
- Use a ball point or stretch needle. The are for sale at any sewing store. Universal needles can poke holes in knit fabric. You may also want to consider ball point pins.
- If you have a walking foot use your walking foot. If not try not to stretch the fabric as you sew.
- For that matter if you have a serger use your serger.
- If you are using your regular machine you either want to use a stretch stitch (check your manuel) or a zigzag. I usually use a zigzag because I like it better then my machines stretch stitch for most knit projects. The only exception is the crotch seam for leggings but that is not an issue here.
- I sometimes use wolly nylon in my bobbin to help with the stretching a bit more. It comes on a cone and is available in the thread section at most sewing stores. Its not 100% necessary though.
stitch witchery before sewing over it with a zigzag stitch. I don't trust it to hold without actually sewing over it but I think the stitch witchery makes it much easier to get nice even hems. It also adds some stability.