So you're ready to call your project finished? First we have to get those stitches back off the needle in a way that will finish up that edge so all your hard work won't unravel.
This is known as binding off -- or sometimes as casting off -- and it's really simple to do. First you knit two stitches in the normal way, then use your left-hand needle tip to pick up the first stitch you knit and slide it up and over the second stitch you knit and the tip of the right knitting needle, leaving one stitch on the needle (or check out binding off in detail).
Continue in this manner until you're down to one stitch on the right needle and none on the left. Cut your yarn that's attached to the ball, leaving 6 inches or so. Slide that last loop off the knitting needle and thread the yarn through it. Pull tight and you're done (well, almost)!