If you mean a wrap, like a Moby-style wrap, they are super easy to make! I know next to nothing about crafts/sewing, and I made one in about 10 minutes.
You just buy 5.5 yards of stretchy fabric (for babies up to about 15 pounds) or woven fabric (for heavier babies), cut it to a 23-inch width, and that's it! With a woven fabric, you'll have to hem all around the edges to prevent fraying, but with a stretchy fabric you won't -- I didn't hem mine, and it held up through 6 months of heavy use and lots of washings. To make it easier to find the center for when you put it on, I sewed a button in the middle.Here
are some great instructions for various carries you can do with a wrap.