You need a piece of rebar, I used a 4 foot piece, but it should really be about 5 feet, depending on how many pots, & how big they are. First you clear a space, so you don't have to mow around it. Pound the rebar into the ground a good 6" or more. It has to be good and sturdy. Set the biggest pot over the rebar, threading it through the hole in the bottom. I filled the bottom with rocks to keep it steady, then the potting mix. The next pot, sits IN the potting soil, tipped to one side, also threaded over the rebar. Each pot after the 2nd one will sit on the EDGE of the one under it, tilting the opposite way.
If you look at my picture, you'll see what I mean. It doesn't look as if they are all sitting on one straight piece of rebar, but they are.
Fill each one as you go with potting soil, but not too full....leave about 2" from the top. You'll need room to put in your plants, and you don't want all the soil to run off when you water. Don't put in your plants until it is all assembled.