Grafting is the attaching of one cultivar of tree onto a rootstock of a different cultivar of tree. For example, avocados grown from seed will not bear fruit. However, if you graft a cutting from a productive avocado to a rootstock grown from seed, the resulting tree will produce avocado fruit. There are several different ways to execute a graft. The one that will work in your situation will depend on how close the cutting and root stock are in size and whether you are planning on grafting more than one cutting to a root stock. However, the simplest graft is the splice graft. The splice graft is best when your scion and rootstock are the same size.
Make a diagonal cut 3/4- to 1-inch long on both the rootstock and the scion. The scion and rootstock should be smaller than 1/2 inch in diameter.
Place the two cuts together and wrap them with grafting tape or twine. Make sure that the cambium--the area just under the bark of the cutting--of the scion and rootstocks meet as much as possible. Wrap about 1/2 to 1 inch above and below the ends of the graft to help stabilize the graft while knitting.
Cover the wrapped graft with grafting wax or paint to help seal the wound and prevent infection.
Water your plant conservatively to reduce the risk of problems while the graft is knitting. Keep the soil moist, but not wet.
Remove the grafting wax or paint and tape or twine once the scion begins to grow buds or leaves.