I was browsing on SHTFM this morning when I ran across a post on these.
Basically they are a fenced in area of four to six feet in diameter. You work the ground in the ring down to around a foot deep.
Fill the chicken wire or poultry cross hatch fenced in area with organic materials. Basically make a compost heap.
Be sure the center is lower then the edges. The center is your watering area. This allows the water to pass through the composting materials. Transferring nutrients from them directly to the soil.
Work the ground around the outside of the ring up to a foot wide area.
Plant your tomato plants equal distances apart around the outside of the ring.
As the tomatoes grow you tie them to the fencing using a soft material. (Some people recommend panty hose for this.)