In some species it is very difficult to get them to root. I think you will be better off buying yoursel an already grafted tree.
But if you insist...: get an one-year old branch of about 8 inches with some buds. At the base, make a cut in an angle as to have a bigger area exposed; dip the base in some rooting hormones; plant it in a pot filled with some sterile (or not contaminated) wet potting mix; using some clear plastic and some wire, construct a little "greenhouse" around the pot; place it in the shade and wait... and wait... and wait. DO NOT TOUCH IT. When you see some leaves remove the plastic. When you notice that the roots are coming through the draining hole you can transplant it.