If you wish to delineate the four quarters to aid you in your visualization, use candles, stones, pine cones, or whatever else nature and your imagination provide.
If you wish to use colored candles the following are good suggestions:Green = NorthIn the past I have also used:
Yellow = East
Red = South
Blue = West
a stone, a bowl of salt = North
a feather, a book = East
a candle = South
a glass of water, a seashell = West
Other ways to outline your circle are left completely to your imagination. On the beach use a stick to draw the circle's outline in the sand. In a rocky area, use a ring of stones. Around a fire, use the logs that later will be your seats. The possibilities go on and on.
You can set up the altar itself in the center of the circle facing North or East, along the North edge, or along the East edge. I prefer to set up my altar along the North edge when performing my rituals indoors, as I simply don't have the space to allow for a large enough circle to have the altar in the center.
Goddess God Symbol Symbol Bowl of Salt Cauldron Censer Pentacle Chalice Incense Bolline Crystal Athame Wand Bell Book of ShadowsMost of these don't require an explanation, but some need just a little. notably the Goddess and God symbols, and the general layout of the altar.
The simplest way to explain the layout of the altar is to divide them into masculine and feminine. Masculine items are on the right, and feminine are on the left, with a bit of overlap in the center. combine that concept with the directions of the elements, and what objects represent which elements, and it makes sense.
The Goddess Symbol - most often used is a candle but other possibilities exist, such asa holed stone, or a statuette of a feminine deity. The candle may be white, blue, green, or silver; most often white or green.
The God Symbol - like the Goddess symbol candles are most often used, but other symbols are possible, such as a horn, acorn, or statuette of a masculine deity. The candle may be white, red, orange, or gold; most often white or red.
Stangs seem to me to be ideal for outdoor rituals, but I have yet to make myself one. I don't get the opportunity to do outdoor rituals as often as I would like.