Tying off is performed once there is only 1 stitch left on the needle.
Using the needle increase the size of the stitch loop by pulling more yarn into it. Break or cut the yarn using a long tail to allow it to be sewn in.
Using the needle pull the free end of the yarn through the center of the stitch.
Keep manipulating the yarn until all the free end of the yarn has passed through the center of the stitch.
It may be necessary to cut the yarn if it is still attached to a large ball of yarn.
However remember to allow at least 15cm (6 inches) to sew in.
Pull the yarn tight. The loop of the stitch will pull tight locking the yarn in place. The end of the yarn can then be sewn in.