These directions are for a square hollow pole that is fixed into the ground; the top was removed by the previous house owners, so the pole was about 7' tall. The pole is a little bigger than 4" x 4", so the wooden 4" x 4" will slide right inside it. You just need to add the backboard and hoop, and something to keep the wood 4" x 4" from sliding all the way into the hollow pole, that is, keep it so the height of the hoop is at least near the 10' regulation height.
Do you have an old basketball pole in your yard? Do you want a very inexpensive way to add the backboard and hoop so you can play? Go to your home improvement store for the few materials; try their "cull" (scrap) section for the plywood, which they may even cut for you if needed. Check out the thrift stores for an old hoop, and go to a sports store for the net. Line up a couple of people for the final assembly, though; this is very awkward to slide into the pole!