You will need root stock to graft onto. You can buy root stock from a nursery, giving you a choice of attributes best for your needs. You can grow your own by planting seeds from apples, taking a chance on what you get. Probably producing a tree that will take twice as long to bear the first apple. May also grow 30 feet tall. Al

Check out YouTube. Stephen Hayes has a lot of videos for a noob. I never knew a thing about grafting until this spring and watched his videos. Three months later I'm now top working my 60 year of tree and made it a 5 in 1 with an additional 4 varieties probably next year. I also have several rootstock trees that I've made into a stooling bed and did a bench graft on another (about ~90 percent success for everything!). All of this was primarily with info from Stephens channel. It's actually really good and very accessible to a complete rookie!