To knit a Christmas stocking, you'll need to know how to knit and purl. First, cast on the number of stitches you need for the width of your stocking. Then, work in the round to make a tube for the leg of the stocking. For the heel, you'll need to work a series of short rows to create a triangular shape. Once you've finished the heel, continue working in the round to create the body of the stocking. Finally, you'll need to add a cuff and a hanging loop. You can find detailed instructions and patterns online or in knitting books.