There are two fairly easy methods for creating a ribbed edge with crochet. This first method works by making stitches in only the back loops of the previous row, at right angles to the main body of your project.

You can add this ribbed edge to pretty much any crocheted or knitted item! Choose your yarn and hook to suit the work you have already completed. Yardage required will depend on the size of the item you are edging.